Abstract: Organic geochemical characteristics of the Jurassic and Carboniferous-Permian melamudstone in well An'can-1 were studied preliminarily by means of the biomarker analysis technology combined with other geochemical data. The results revealed thet two sets of dark strata have lower organic matter abundance, their organic mother matter is dominated by low-grade hydrobios mixed with high-grade plants, and the type of organic matter is humosapropelic. The high maturity for the thermal evolution of organic matter shows that the hydrocarbon-generating peak has gone, but the strata can still be gas source rock of the area.