Abstract: Dark mudstone and shale of Lower Permian Shoushangou Formation are well developed in Xi Ujimqin Banner of Inner Mongolia. Organic geochemical studies of hydrocarbon source rock samples collected from Tabinmiao forestry center profile were conducted in the aspects of organic matter abundance, kerogen types and maturity of organic matter, so as to evaluate the hydrocarbon potential. Organic matter abundance of Shoushangou Formation in Xi Ujimqin Banner of Inner Mongolia has reached moderate to good hydrocarbon source rock standard; organic matter was derived mainly from higher plants, and the kerogen belongs to type Ⅲ. Thermal evolution of organic matter entered into the mature to over mature stage. Hence the Shoushangou Formation is the potential hydrocarbon (particularly gas) source rock and serves as another important Upper Paleozoic layer in the peripheral oil and gas exploration of the Songliao basin.