Abstract: Source,depositional environment and thermal maturity indicators from Upper Triassic potential hydrocarbon source rock in Reshui-Muole area of the South Qilian basin have been studied by means of bioma rker analysis technology and other geochemical methods. The potential hydrocarbon source rock,mainly composed of sediments deposited in predelta and lake basin bogenvironment,has a high abundance of organic matter. The humic and mixture types of organic matter indicate that they were derived mainly from higher plants with some inputs of lower marine organism. Analysis data and related parameters also indicate that the organic matter has developed mature. All these suggest that source rocks are developed in upper Triassic strata of the studied area and their oil-generating potential is relatively high.