///The genetic classification and source rock identification are analyzed, based on crude oil and source rock samples systematically in Wuhaozhuang area of Zhanhua sag. The result shows that there are three types of crude oil in origin. Type -Ⅰoil derived from the first member (Es1) of Shahejie Formation. Class -Ⅱoil and Class -Ⅲoil generated from the fourth member (Es4) and the third member (Es3) respectively. Class -Ⅰ oil is characterized by high gammacerane index, low maturity, low diasterane and 4 - methylsterane, reflecting that the biological source of crude oil would mainly be composed of low - grade aquatic thallophyta and algae, which coccolithophoridae and diatom would have more contribution to it, and the source rock would have been deposited in brackish and reducing sedimentary environment. Class -Ⅱ oil and Class -Ⅲ oil by low gammacerane index, high maturity, high diasterane and 4 - methylsterane, which the gammacerane index of the former is higher than that of the latter, indicate the source rock would have been deposited in fresh - slightly saline water and weak redox environment. The gammacerane index of t Class -Ⅱ oil is higher than that of Class -Ⅲ oil, suggesting the sedimentary environment of the source rock of the former would have had more salinity. Meanwhile terrestrial plants input more for Class -Ⅱ oil than Class -Ⅲ oil.