There are few national statistical data on Buddhist Monasteries of Yuan Dynasty.Therefore,the "Stele Inscription of Reading Sutras in One Hundred Huge Monasteries",by a Uyghur navigator named Yighmish,was a significant source.This paper first discusses the discovery of this stele and the quality of different collections of its epitaph copies,and then analyses the biography of Yighmish and his motive to build this stele.The author argues the activities of reading and chanting sutras was correlated with the cult of the great treasury of Buddhist Sutras in the Yuan Dynasty.Finally,he analyses the geographical distribution of Mahayana Buddhist monasteries in the Yuan Dynasty based on the information in the stele.