The basic sūtra of Yogācāra School is ”Samdhi Nirmocana Sūtra”, whose thought of ”Three Period Teaching Classification” becomes one of the basic prerequisites for the development of Indian Buddhist thought about teaching classification, especially the criterion for the teaching classification of Yogācāra School. This paper tries to carry on a comparative analysis to the two Chinese and one Tibetian texts of ”Three Period Teaching Classification” of ”Samdhi Nirmocana Sūtra”, in order to make a deep inquiry for the significance and intention of the teaching classification of this sūtra.