According to geochemical characteristics in combination with thermal evolution, there exist mainly three sets of source rocks in Sikeshu depression of Junggar Basin, namely Jurassic (Badaowan Formation, Sangonghe Formation and Xishanyao Formation), Cretaceous and Paleogene. Through oil-source rocks correlation and quantitative identification of mixed oil, it is concluded that the crude oil in Chepaizi area was mainly derived from the Jurassic source rock in Sikeshu Depression and mixed with the immature crude oil from the Cretaceous source. It is inferred that coal-formed oil dissolved the biomarker-rich Cretaceous bitumen of relatively low thermal maturity, and overprinting occurred during oil migration.