Abstract: The main source rocks of the Changling Fault Depression in the Songliao Basin are dark mudstone and coal seam deposited in the Lower Cretaceous Shahezi Formation.The Huoshiling and Yingcheng Formations are secondary source rocks.Analyses of well samples and outcrops show that,as to the Huoshiling Formation source rocks,organic carbon content is 0.50%-8.55%,hydrocarbon gene-ration potential is 2-17 mg/g,chloroform bitumen "A" content is 0.04%-0.33%,main kerogen type is Ⅱ,and it is during the over-mature stage of organic evolution.As to the Shahezi Formation source rocks,organic carbon content is 1.00%-6.54%,hydrocarbon generation potential is 2-8 mg/g,chloroform bitumen "A" content is 0.2%-0.5%,main kerogen types are Ⅰ and Ⅱ,and it is during the high-and over-mature stages of organic evolution.As to the Yingcheng Formation source rocks,organic carbon content is 0.5%-2.5%,hydrocarbon generation potential is 0.5-4.0 mg/g,chloroform bitumen "A" content is 0.05%-0.20%,main kerogen type is Ⅱ,and it is during the mature and high-mature stages of organic evolution.The Shahezi Formation source rocks are considered as moderate-good,while the Yingcheng and Huoshiling Formations are considered as moderate.