Abstract The dolostone of the Changxing Formation in Sichuan Basin is an important target of the exploration of petroleum. The Panlongdong profile is the best outcrop in northeast Sichuan, and the research of diagenesis of this profile is of vital importance for understanding the formation and evolution of Changxing reservoirs. The fabric and occurrence of dolostone contains genetic information. With the help of CL, we found that fabrics of dolostone can be divided into two types: uniform and heterogeneous, and the coarse dolomites are developed from the fine dolomites. The growth of coarse dolomites is directional. Based on the research of diagenesis（combined with fluid inclusion thermometry）, statistics analysis of contents and sizes of dolomites for the first time. The statistic result shows that the content and size of dolomite gradually reduced downward, which indicates that the dolomitization fluid migrated downward, and the prevailing mimetic dolomitization proves evidence of penecontemporaneous dolomitization.