Based on the soluble organic matters, biomarkers and vitrinite reflectance, this paper analyzed comprehensively thermal evolution characteristics of Paleogene source rocks and their main controlling factors in different subsags within the northern part of Dongpu depression. The results show that Paleogene source rocks of both Qianliyuan and Haitongji sags have developed into high and over-mature stages, while Paleogene source rocks of Puwei subsag only belong to the mature stage.