Abstract: Tailing pond is a place for stockpiling mining industrial waste.According to the new national environmental protection law and the new code for design of tailings facilities，the environment-friendly anti-seepage design of category II tailings pond must be carried through，and the performance of the anti-seepage must meet regulatory requirements.The anti-seepage system is a crucial part of category II tailing pond，which can segregate the tailing and slurry water in the tailing pond from outside effectively，and prevent tailings water from polluting environment.the technical characteristics of HDPE film and geosynthetic clay liner，the structure design of anti-seepage layer in the environmental anti-seepage system，the major technical requirements of anchoring platform and anchoring ditch were mainly discussed.It is pointed out that the problems of adding recycled material，temperature difference in alpine region and the film thickness should be paid attention，when HDPE film is used.For the bentonite，it is suggested to choose sodium base bentonite.Bentonite waterproof blanket is not suitable for waterproof and anti-seepage project in high potency electrolyte solution.For the anti-seepage structure layer，it is determined by the factors of the permeability coefficient of the local tailing pond，and the single layer of the artificial composite anti-seepage structure is promoted according to the actual effect of anti-seepage engineering at home and abroad.

Key words: Tailing pond, Industrial solid wastes, Category II tailing pond, Environmental protection, Anti-seepage, HDPE film, Geosynthetic clay liner