In this paper, the IES basin modeling method and the model of Easy%R_o are firstly used to analyze the single well thermal history and the hydrocarbon generation history. The third member of Shahejie Formation (Es₃) and the fourth member of Shahejie Formation (Es₄) are the major source rocks in Laizhouwan Sag. Based on the study of the single well thermal history and the hydrocarbon generation history, the hydrocarbon states of the two major source rocks in different periods and different areas are discussed. It is shown that the 5.1Ma before the third member of Shahejie Formation (Es₃m) source rock goes already at the top oil window and the fourth member of Shahejie Formation source rock is in the stage of the hydrocarbon generation and is discharged into the northern sag. Now the two major source rocks are both in the stage of the hydrocarbon generation and are discharge into the northern sag and the fourth member of Shahejie Formation source rock is at the hydrocarbon peak in the center of the Northern sag.