Abstract The original version of Yuelilizhi in Chongzhen Lishu is studied in this paper. Based on the comparison study, it thinks that the observation and the calculation of the lunar mean motion in Greece were introduced in Yuelilizhi. And these materials are from Ptolemy’s Almagest. They have been studied in this paper that some concept and geometry explaining of the lunar mean motion, and Ptolemy’s method founded on the observation and the hypothesis, and his demonstration based on the Euclid’s Element. It is found that there were some disadvantages in the astronomical observation of the ancient China.