Sima Qian was born and grew up in Longmen, near present-day Hancheng, Shaanxi. He was raised in a family of astrologers. His father, Sima Tan, served as the Prefect of the Grand Scribes of Emperor Wu of Han (Emperor "Han Wudi"). His main responsibilities were managing the imperial library and maintaining or reforming the calendar. Due to the intensive training given by his father, by the age of ten, Sima Qian was already well versed in old writings. He was the student of the famous Confucians Kong Anguo (??? or ???) and Dong Zhongshu. At the age of twenty, with the support of his father, Sima Qian started a journey throughout the country, collecting useful first-hand historical records for his main work, Shiji. The purpose of his journey was to verify the ancient rumors and legends and to visit ancient monuments, including the renowned graves of the ancient sage kings Yu and Shun. Places he had visited include Shandong, Yunnan, Hebei, Zhejiang, Jiangsu, Jiangxi and Hunan.

After his travels, he was chosen to be a Palace Attendant in the government whose duties were to inspect different parts of the country with Emperor Han Wudi. In 110 BC, at the age of thirty-five, Sima Qian was sent westward on a military expedition against some "barbarian" tribes. That year, his father fell ill and could not attend the Imperial Feng Sacrifice. Suspecting his time was running out, he summoned his son back to complete the historical work he had begun. Sima Tan wanted to follow the Annals of Spring and Autumn - the first chronicle in the history of Chinese literature. Fueled by his father's inspiration, Sima Qian started to compile Shiji in 109 BC. In 105 BC, Sima was among the scholars chosen to reform the calendar. As a senior imperial official, Sima was also in the position to offer counsel to the emperor on general affairs of state.

In 99 BC, Sima Qian became embroiled in the Li Ling Affair: Li Ling and Li Guangli (???), two military officers who led a campaign against the Xiongnu in the north, were defeated and taken captive. Emperor Han Wudi attributed the defeat to Li Ling, and all the officials in the government condemned Li Ling for the defeat. Sima was the only person to defend Li Ling, who had never been his friend but whom he respected. Emperor Han Wudi interpreted Sima’s defence of Li Ling as an attack on his brother-in-law, who had also fought against the Xiongnu without much success, and sentenced Sima to death. At that time, execution could be commuted either by money or castration. Since Sima did not have enough money to atone his "crime", he chose the latter and was then thrown into prison, where he endured three years. He described his pain thus: "When you see the jailer you abjectly touch the ground with your forehead. At the mere sight of his underlings you are seized with terror... Such ignominy can never be wiped away."

In 96 BC, on his release from prison, Sima chose to live on as a palace eunuch so as to complete his histories, rather than commit suicide as was expected of a gentleman-scholar. As Sima Qian's words explained:

Although the style and form of Chinese historical writings varied through the ages, Shiji has defined the quality and style from then onwards. Before Sima, histories were written as certain events or certain periods of history of states; his idea of a general history affected later historiographers like Zheng Qiao (??) in writing Tongshi (??) and Sima Guang (???) in writing Zizhi Tongjian (????). The Chinese historical form of dynasty history, or Jizhuanti history of dynasties, was codified in the second dynastic history by Ban Gu’s (??) History of Han (??), but historians regard Sima’s work as their model, which stands as the "official format" of the history of China.

In writing Shiji, Sima initiated a new writing style by presenting history in a series of biographies. His work extends over 130 chapters — not in historical sequence, but was divided into particular subjects, including annals, chronicles, treatises — on music, ceremonies, calendars, religion, economics, and extended biographies. Sima's influence on the writing style of histories in other places is also evident in, for example The History of Korea.

Sima's Shiji is respected as a model of biographical literature with high literary value, and still stands as a "textbook" for the study of classical Chinese worldwide. Sima’s works were influential to Chinese writing, serving as ideal models for various types of prose within the neo-classical ("renaissance" ??) movement of the Tang-Song (??) period. The great use of characterisation and plotting also influenced fictional writing, including the classical short stories of the middle and late medieval period (Tang-Ming), as well as the vernacular novel of the late imperial period.

The influence is derived from the following key elements of his writing:

Skillful depiction

Sima portrayed many distinguished subjects based on true historical information. He would illustrate the response of the subject by placing him in a sharp contrast or juxtaposition, and then letting his words and deeds speak for him. The use of conversations in his writing also makes the descriptions more vibrant and realistic.

Innovative approach

Sima's new approach in writing involved using language that was informal, humorous and full of variations. This was an innovative way of writing at that time and thus it has always been esteemed as the highest achievement of classical Chinese writing; even Lu Xun (??) regarded Shiji as "the unique work of all historians, the songs of Qu Yuan without rhyme."(???????????) in his Hanwenxueshi Gangyao (????????).

Concise language

The style was simple, concise, fluent, and easy-to-read. Sima made his own comments while recounting the historical events. In writing the biographies in Shiji, he avoided making general descriptions, and instead tried to catch the essence of the events. He would portray the subjects concretely, giving the readers vivid images with strong artistic appeal.

Other literary works

Apart from Shiji, Sima wrote a famous letter to his friend Ren An, in which expressed his suffering during the Li Ling Affair and his perseverance in writing Shiji. This letter is a highly admired example of literary prose style and is widely studied in China even down to the present. Sima Qian had written eight rhapsodies (Fu ?), which are listed in Hanshu bibliographic treatise. All but one of these have been lost. The only one to survive, the "Rhapsody in Lament for Gentleman who do not Meet their Time" ????, is probably not complete.

Sima and his father were both court astrologers (taishi) ?? in the Former Han Dynasty. At that time, the astrologer had an important role, responsible for interpreting and predicting the course of government according to the influence of the Sun, Moon, and stars, as well as other phenomena like solar eclipses, earthquakes, etc.

Before compiling Shiji, in 104 BC, Sima Qian created Taichuli (which can be translated as 'The first calendar') on the basis of the Qin calendar. Taichuli was one of the most advanced calendars of the time. The creation of Taichuli was regarded as a revolution in the Chinese calendar tradition, as it stated that there were 365.25 days in a year and 29.53 days in a month.

Sima adopted a new method in sorting out the historical data and a new approach to writing historical records. He analyzed the records and sorted out those that could serve the purpose of Shiji. He intended to find out the patterns and principles of the development of human history.

Sima emphasised the role of men in affecting the historical development of China. It is the first time in Chinese history that men were put under the spotlight in the analysis of historical development. He also denounced Emperor Han Wudi, who was superstitious, and prayed to gods extravagantly. In addition, he also proposed his historical perception that a country cannot escape from the fate of the boom-bust cycle. With these in-depth analyses and insight, Sima set an example for writing journalistic articles in later generations.

Unlike Hanshu, which was written under the supervision of the Imperial Dynasty, Shiji was a privately written historiography. Although Sima was the Prefect of the Grand Scribes in the Han government, he refused to write Shiji as an official historiography covering only those of high rank. The work also covers people of the lower classes and is therefore considered a "veritable record" of the darker side of the dynasty.

The minor planet 12620 Simaqian is named in his honour.