The underground cavity is the hydroelectric project common building. Cavity water creep and drainage arrangement does not focus attention on frequently in the engineering construction initial period by the constructor. But to later period, even after the power generation, It will bring many thorny matters. Xilongchi Pumped-storage Power Station is too. For power plant construction, The constructor adopts many means for solution the question. This article has carried on the summary discussion to it, and hoped that draws out the question value.