Hydrocarbon source conditions in Sanhecun area of Zhanhua sag are complex and hydrocarbon distribution rules are not clear，which constrain the exploration in the area. The hydrocarbon sources and migration pathways have been analyzed systematically based on crude oil physical properties，biomarker and carbon isotopes and maturity parameters. The results obtained show that the crude oil in the Sanhecun area is classified into two types：Es4 type crude oil and mixed crude oil. The former is migrating from hydrocarbon rocks in the 4th member of Shahejie Formation in Bonan subsag，and the latter is migrating from both the hydrocarbon rocks in the 4th member of Shahejie Formation in Bonan subsag and the rocks in the 3rd member of Shahejie Formation in Gunan subsag. It is known that the main crude oil filling direction is from the northeast to the southwest according to the analysis of tracing index of hydrocarbon migration. Combining with the analyses on structures and hydrocarbon scale，the favorable traps in the sub-depression of the northern subsag and in the nose structure of southern Gudao uplift are the next exploration targets.