Based on 1500 thin sections from 20 wells，It was found that two kinds of dolostone reservoirs of Triassic Leikoupo Fm. in Sichuan basin. Having undergone complicated diagenesis, the pore space in the reservoirs developed into residual primary intergranular and gypsum-dissolved pores at the early diagenetic stage. The substitution of arid and humid climate frequently controlled the reservoirs developed，which resulted in facies-selective distribution of reservoirs.