Chinese mathematician and astronomer.

Li was the son of a widely educated state official. He was given a position in the Imperial Astronomical Bureau in 627, following his critique of the Wuyin calendar, which had been introduced in 619. Later he submitted a report concerning the outdated astronomical instruments used in the bureau and was ordered to make a new armillary sphere; it was accomplished in 633 according to his design, which added a third ring to the traditional two-ring structure.

Li became the deputy director of the Imperial Astronomical Bureau about 641. He participated in the compilation of the official histories of the Jin (Jin dynasty) (265–420) and Sui (Sui dynasty) (581–618) dynasties, writing the chapters containing historical outlines of Chinese astronomy, astrology, metrology, and a mathematical theory of music. In 648 he became the director of the Imperial Astronomical Bureau, and, with Liang Shu and Wang Zhenru, he edited a collection of mathematical treatises used as manuals in the Mathematical College of the State University. The edition traditionally referred to as Shibu suanjing (“Ten Mathematical Canons”) was submitted for formal approval to the emperor in 656. Later Li prepared a new calendar, the Linde calendar, which was promulgated in 665 and used until 728. Because of his reputation as a skillful astrologer, some works on divination and esoteric practices were later credited to him.