Abstract: The penetration of the tail slurry suspended particles leads to the phenomenon of clogging in tailing dam，and a higher seepage line impacts on stability of tailings dam.First of all，the influencing factors of muddy water infiltration are studied，then an indoor simulation experiment is made according to the former study to obtain the general law of the general regularities of variation of the coefficient of permeability of muddy water infiltration by using a self-made muddy water seepage test instrument.According to the regularities，the related design parameters of a tailings dam is corrected，and the permeability function is estimated through particle size distribution curve which is obtained by laser particle size analyzer.Then the original and the adjusted parameter are respectively input to Geo-Studio SEEP/W module in seepage field simulation，obtaining the position and form of saturation line under two kinds of situations.Finally the simulation results are plug in the SLOPE/W module，to simulate dam body stability under three kinds of working conditions at the time of the high end.The result shows that the stability safety coefficients are all in a certain degree of decrease.Therefore，it comes to a conclusion that the stability of tailings dam can be reduced by the siltation.

Key words: Muddy water infiltration, Seepage line, Permeability coefficient, Size distribution, Siltation effect, Safety factor