It is important to clarify the hydrocarbon generating potential and oil- source relationship of the Paleogene source rocks in the Qinnan Sag, Bohai Bay Basin.Methods: The characteristics of the source rocks and crude oil from different strata were analyzed, and oil- source correlation were conducted by using multiple geochemical data. Results: The Es3 and Es1 Members ( the 3rd Member and the 1st Member, Shahejie Formation, Eocene) are high- quality source rocks with type I and II kerogen. They are dominated by aquatic organic matter and formed in an anoxic freshwater and brackish water environment, respectively, wiht high hydrocarbon generation potential. The Ed3 Member is a fair- quality source rock with type II and type II—III kerogen. They are characterized by mixed organic matter and developed in a dysoxic freshwater environment, with medium hydrocarbon generation potential. There are various types of crude oil in the Qinnan Sag, including light oil, condensate oil and heavy oil from deep to shallow. Typical biomarker compound parameter distribution characteristics are similar, manifested as similar relative content of C27 and C29 regular steranes, low ratios of C19/C23 tricyclic terpenes, C20/C23 tricyclic terpenes, and C21/C23 tricyclic terpenes, low ratios of Pr/Ph, moderate gammacerane indexs, moderate sterane isomerization parameters and pregnane parameters. Based on comprehensive analysis, the deep and shallow oil and gas in the Qinnan Sag are homologous, representing a mixed contribution of the Es3 and Es1 source rocks with higher maturity in the depression zone. Conclusions: The findings in the study can provide a basis for further understanding of the rule of hydrocarbon migration and accumulation in the Qinnan Sag, Bohai Bay Basin.