Abstract: To solve the disputes on oil source in Tahe oilfield of Tarim basin, the paper selects the oil obtained from Well TK772 in the major area of the oilfield to comparatively study the geochemical characteristics of the crude oil and the hydrocarbons occluded in the asphaltene oxidation products. The results show that the hydrocarbons occluded in asphaltene are characterized by even carbon preference in N-alkanes, low pristane to phytane ratio, low C29/C30 hopane ratio, low C35/C34 hopane ratio, low maturity, high Ts/(Ts+Tm) ratio and high gammacerane index and so on, indicating that its oil source was formed in an evaporite environment with restricted platform, high salinity, strong reduction and zonal water body, which represents the oil charging characteristics at the earliest stages in Tahe oilfield. The characteristics of the biomarkers of saturated hydrocarbon in Well TK772 which is significantly different from that of the hydrocarbons occluded in asphaltene reflects that its oil source was formed in a depositional environment of carbonate rocks with broad water body and low salinity, representing the characteristics of the most oil in Tahe oilfield. Based on these newly obtained geochemical evidence and combined with the previous research results on the relationship between source rock distribution and sedimentary facies in the northern Tarim basin, it is considered that the oil accumulated in 3 periods in Tahe oilfield, the first-period oil originated from the Cambrian source rocks of evaporite facies in the platform; the second-period oil from the Upper Ordovician carbonate source rocks and the third-period from the high-maturity light oil charging at the late stage in the periphery of Tahe oilfield