Xin Yi Xiang Fa Yao is a book that records the shape and principle of operation of the large astronomical instrument water-powered astronomical clock tower in the Northern Song Dynasty，divided into three volumes. There are five star charts in the volumes (two horizontal charts and three cover charts)．As recorded in Xin Yi Xiang Fa Yao: water-powered astronomical clock tower was built in the Northern Song Dynasty，and was a large-scale astronomical instrument set up under the directing of Su Song and Han Gonglian. It is a square wood structure building that is narrow on the top and broad at the bottom and the armillary sphere etc are made of copper. The entire tower is divided into three compartments，and the under compartment includes a timekeeping device and actuating unit of the entire tower etc; the middle compartment is a secret room for storing armillary sphere；he upper compartment is a board house，which stores the armillary sphere. This topic focuses on the armillary sphere star chart of the water-powered astronomical clock tower．According to the existing materials，only five star charts in the Xin Yi Xiang Fa Yao can be used as the most intuitive data for studying the armillary sphere star chart. There are no related star tables and data come down. Through analyzing and comparing the star charts of the existing several versions of Xin Yi Xiang Fa Yao ， mainly include Complete Library in Four Branches of Literature，Series Integration，Universal Libraries，Ningbo Tianyi Pavilion Collection Shoushan Pavilion Series，Nanjing Library Collection Holding Yi Xiang Fa Compiled Version，the Series Integration is selected as the star chart version that is most suitable for analyzing the star position. Finally，according to the precession theory of modern astronomy，use the celestial precession nutation P03 model issued by the IAU International Astronomical Union to calculate the historical right ascension and declination data of star described in the star chart， choose the determinative star of each star in the horizontal chart as the study sample ， calculate the celestial coordinate data of the star sample in this star chart from AD 600 to AD 2000 under Matlab 2009 matrix laboratory platform calculate the average deviation and standard deviation values of the sample by comparing this sample data and measurement data of the star chart. By combining the statistic analysis，predict the accuracy and observation years of the star position，and draw the conclusion that the observation years of the stars drawn according to the star chart of the Xin Yi Xiang Fa Yao are the Yuanfeng reign of the Northern Song Dynasty.

This presentation is based on work co-authored by Guoqiang Li.