The development of Karst seepage channel is a major safety hazard to the hydropower projects, and therefore the identification of the presence or absence of seepage channel in the water conservancy and hydropower project is an important work. Tracer method is a popular method in terms of detecting the existence of seepage channel , because this method can detect the connection between each test points and then determine the process of groundwater movement. In this paper, tracer test was applied in the left abutment of a hydropower station in Western China, which detected the presence of seepage channel between each test points.