Abstract: Based on analysis of the regional geological background, northeastern China is in the tectonic background of active continental margin, and formed pan-basin of Carboniferous-Permian. Formation and evolution of Songliao Basin was on the residual basins of Carboniferous-Permian with the area of 7.2×104km2. The geochemical analysis showed that Permian strata mainly composed of extremely low class metamorphic rocks, and the mudstone of Permian had the high organic matter maturity and abundance and the low residual hydrocarbon generation potential. Permian mudstone of basin eastern with the thickness over 1000m is in the over-mature stage possessed the hydrocarbon generation potential up to now, and the organic maturity of which is less than that of northern basin and western basin. Since the sedimentary of Mesozoic formation, Permian mudstone of eastern basin with larger increase amplitude of organic maturity has happened the secondary hydrocarbon generation of the great hydrocarbon generating quantity, which can be preserved effectively and form primary and secondary reservoir. The mudstone had better exploration prospect.