Through analyses of TOC，Rock-Eval，biomarker compositions and drill and seismic data，this study was undertaken to investigate the hydrocarbon generation potential，organic matter types，organic matter input and sedimentary and preservation environment of source rocks in the Baxian Sag. Based on source-related biomarker parameters of the source rocks and oil，a detailed oil-source correlation was conducted to identify the origin of oil and to evaluate hydrocarbon contributions of each set of source rocks. The result shows that there are four sets of high-quality source rocks developed respectively in the fourth member of Shahejie Formation（E2s4），the lower third member of Shahejie Formation（E2s3L），the middle third member of Shahejie Formation（E2s3M）and the lower first member of Shahejie Formation（E3s1L），among which hydrocarbon source rocks in E2s4，E2s3L and E2s3M are distributed widely and the source rocks in E3s1L are only distributed in the southern of the studied area. And these source rocks are characterized of good type of organic matter and great potential for hydrocarbon generation and expulsion. The four sets of hydrocarbon source rocks have entered into hydrocarbon generation threshold and are thermally mature. The characteristics of biomarker parameters reveal that the original input and sedimentary preservation environments of organic matter are different. The source rocks in E2s4 and E2s3L have more abundant organic matter supply than those in E2s3M and E3s1L，however，sedimentary preservation conditions at the stages of E2s3M and E3s1L are relatively poor. From the oil-source correlation，three oil families were derived from the source rockes in E2s4，E2s3L and E3s1L respectively，and two types of mixed oil were identified. By analysis of hydrocarbon generation potential of the source rocks，their spatial distribution and distribution of their related traps，it is concluded that the main hydrocarbon source rocks for traps that have found are developed in E2s3M-L. The source rocks in E2s4 have high quality and great potential for hydrocarbon generation and expulsion. E2s4-derived oils migrated for a short distance and dispersedly accumulated in the deep or buried-hill traps near the kitchen，but only a few of them have been found. Such a petroleum distribution pattern has important implications for future exploration. There is considerable exploration potential for E2s4-derived oils in the deep traps and buried-hill traps in the Baxian Sag.