Abstract: By means of whole-rock analysis of organic petrology,the maceral composition,hydrocarbon-generating maceral and thermal evolution of organic matter of hydrocarbon source rocks in Majiang-Kaili area of the southeastern Guizhou province have been studied.The source rock samples from this region mainly include 3 types: bitumen-bearing carbonates,mudstones and coals.The maceral contents of these source rocks vary according to their different samples,showing obviously heterogeneity.The total maceral contents (TMC) of the bitumen-bearing carbonates,mudstones and coals are 0.8%-13.6%,1.4%-9.4%,and over 70%,respectively.The hydrogen-rich macerals of these hydrocarbon source rocks are mainly composed of exinite,asphalt group,secondary organic matter and mineral bituminous groundmass.It is suggested that sporinite,liptodetrinite,bitumen and mineral bituminous groundmass are the main hydrocarbon-generating macerals in this region.Thermal evolution level of organic matter in these hydrocarbon source rocks are among the mature and over-mature stage,with the equivalent vitrinite reflectance (R_o) of 0.674%-2.659%.