Abstract: In order to comprehensively and effectively recognize source rocks in Yingcheng Formation of Shuangcheng area in Songliao Basin, the geochemical pyrolysis and molecular organic geochemistry characteristics of drilled core are analyzed, high-abundance mature source rocks have been found for the first time. Combining sequence stratigraphy and geophysical techniques, the distribution law of high-quality source rocks is determined. It was recognized that the average total organic carbon (TOC)content is 2.46%, the organic matter is mainly Ⅱ type, there are a plenty of aquatic algae in organic matter, and the vitrinite reflectance (R_o)is in a range of 0.8% -1.0%, so the source rocks are in the peak hydrocarbon-generating stage. A relatively stable tectonic background of fault depression conversion period is a favorable environment for source rocks deposition, low Pr/Ph ratio of nalkane proved favorable environment for the preservation of organic matter. The high-quality source rocks mainly developed in the transgressive system tract and highstand system tract of sequence SQ1 and sequence SQ2, the thickness of high-quality source rocks in SQ1 is generally 20-80 m, while the thickness of high-quality source rocks in SQ2 is generally 10-30 m. The oil source correlation shows that the high-quality source rocks in Shuangcheng area are the direct hydrocarbon source for the reservoir, and the discovery of high-quality source rocks in Shuangcheng area provides reference for other peripheral fault depression exploration.