Shen Kuo is also an outstanding astronomer. In the fifth year of Xining (A.D. 1072), when he was in charge of Bianhe construction in Shen Kuo, Shen Kuo was also in charge of leading the Tianjian Supervision Department. During his tenure, he successively dismissed six uneducated old calendar officials, regardless of their origins, and recommended Wei Pu, a Huainan native who was proficient in astronomical calendar calculation and was born in a civilian, to enter the Tianjian Supervision Department to preside over the important work of revising the new calendar. Shen Kuo and Wei Puzhi took a serious attitude and were very dissatisfied with the calendar revision method that the old calendar officials relied on calculus. They advocate starting with observing the astronomical phenomena and taking the measured results as the basis for revising the calendar. Therefore, Shen Kuo first studied and reformed the old astronomical observation instruments, such as armillary sphere, floating leak and shadow table.

The armillary sphere is an instrument for measuring the orientation of celestial bodies. After the development and evolution of the past dynasties, by the Song Dynasty, the structure of the armillary sphere had become very complicated, three times, intertwined and inconvenient to use. Therefore, Shen Kuo reformed the armillary sphere for many times. On the one hand, he canceled the small white ring, simplified the instruments and division of labor, and then linked the relationship between them with mathematical tools ("the moon ring is omitted, and the difference between the moon and the moon is only a step based on the calendar"); On the other hand, it is suggested to change the position of some rings so that they do not block the line of sight. These reform measures in Shen Kuo have opened up a new road for the development of musical instruments. Later, in the 13th year of Zhiyuan (A.D. 1276), Guo Shoujing of Yuan Dynasty created a new astronomical instrument-Jane Instrument, which was produced on this basis.

The clepsydra is an ancient instrument for measuring time. It is composed of several water containers in the form of steps, and the lower side of each container has holes, which drip from the next container in turn. There is no hole in the bottom container, but there is an "arrow" engraved with the time scale. As the dripping water level rises, the "arrow" slowly floats, and the time can be read from the exposed scale. Shen Kuo also reformed leaky cauldron. He changed the copper leaky pipe of the curved barrel into a straight-necked jade mouth and moved it to the lower part of the pot body. This makes the running water smoother, and the spout is much stronger and more durable.

In addition, Shen Kuo has formulated the standard for measuring the sun's shadow and improved the method for measuring the shadow.

Shen Kuo introduced his research achievements in three papers: On the Hunyi, On the Floating Leak and On the Landscape, elaborated the principle of instrument transformation in detail, and expounded his own astronomical views, which played an important role in the history of astronomy in China.

A series of innovative activities of Shen Kuo and Wei Pu were attacked and framed by conservative forces. Under the resolute struggle of Shen Kuo and Wei Pu, the revised Fengyuan Calendar presided over by Wei Pu was finally completed and promulgated in the eighth year of JaeHee Ning (A.D. 1075). However, due to the obstruction and destruction of conservative forces, the relatively advanced abundant calendar was abolished after only 18 years. However, Shen Kuo didn't lose heart because of this. In his later years, he further put forward the idea of replacing the original calendar with the "Twelve-qi Calendar". The original calendars in China were all based on the combination of yin and yang, but the "twelve-qi calendar" was a pure solar calendar. The year is divided into four seasons, and each season is divided into three months: Meng, Zhong and Ji, and the month is determined according to the solar terms. Beginning of spring's day is 1 month 1 day, and the day of fright is February 1 day, and so on. Thirty-one days for the big moon and thirty days for the small moon. The big moon and the small moon appear alternately. Even if there is a situation that "two little moons are combined into one", it is only once a year. There are "two small pictures", with 365 days in a year; No, 366 days a year. In this way, the days of the year are very neat, there is no need to set up a leap month, and the four seasons are fixed dates. As for the moon's profit and loss, it has nothing to do with the season when the cold comes and goes, as long as you indicate "new moon" and "hope" in the almanac. The calendar designed by Shen Kuo is scientific, which is not only in line with the reality of celestial bodies, but also conducive to the arrangement of agricultural activities. He foresaw that his ideas would be attacked and scolded by diehard conservatives, and he tried his best to obstruct them, but he firmly believed that "different times will be useful to speakers." Sure enough, nearly 800 years later, the basic principles of the calendar promulgated by the great peasant revolutionary regime, the Taiping Heavenly Kingdom, were completely consistent with Shen Kuo's Twelve Qi Calendars. The Gregorian calendar adopted by countries all over the world, that is, the solar calendar, is actually not as reasonable as the "twelve-year calendar" in Shen Kuo.