Abstract: In this paper,diagenetic features have been studied and diagenetic stages identified for Triassic in the Songpan-Aba area by experimental analysis on diagenetic indicators,such as petrologic analysis on mineral facies,investigations of clay minerals and assemblage features,illite crystallinity determination colibrated to standardized scale(CIS),percent of smectite layer in mixed clay minerals,vitrinite reflectance determination,and thus help the diagenetic study of sedimentary rocks and pool forming conditions.