Abstract: A series of thick mudstone of the Upper Permian Linxi Formation, which is a potential layer for hydrocarbon source rock, is widely distributed in the Jarud Basin. Indexes such as organic abundance, type, source and maturity are used to analyze the outcrop samples from Linxi Formation. The testing result shows that the organic abundance of the mudstone is medium to relative-good degree, belonging to medium grade of hydrocarbon source rock, with organic type Ⅲ. The maximum pyrolysis temperature of organic matter varies from 363℃ to 581℃;The vitimite reflectance is distributed from 1.38% to 2.8% with average of 2,01%. The data suggest that the mudstone of Linxi Formation be in high-and overmature stage. The research reveals that the mudstone of Linxi Formation is a kind of favorable hydrocarbon source rock with good exploration prospect for gas resource.