Abstract: According to the existing data of Songliao Basin and from the aspects of petroleum geology, a discussion is made on the Cretaceous sedimentation environment of Songliao Basin and its relation with oil-bearing strata, and the formation of source material by using the dependence of sporo-pollen fossil assemblage on the Cretaceous sedimentation environment. This paper contains three parts. (1) Brief description of the strata and the sporo-pollen fossil assemblage; (2) Discussion on the paleoclimate and paleovegetation of the stage of sedimentation; (3) Variation of Cretaceous paleogeography and paleoclimate in the Songliao Basin and its relation with the formation of source ma-terial.