Abstract: Seepage control of foundation with the deep overburden layer which can be considered as the infinite deep pervious foundation is one of the key problems that determines the success or failure of dams construction. The suspended cut-off wall has been used as the anti-seepage structure in the same projects, but analysis of its seepage control effects and percolation mechanism has no common understanding in the theory. In order to make deep studies of the seepage control effects and percolation mechanism of the suspended cut-off wall, a model in combination with the infinite element method is established to simulate the infinite deep pervious foundation, analyzing the variation in seepage discharge and seepage gradients under the conditions of different permeability coefficients k, depth of the cut-off wall s and the water head difference ΔH, and fitting out the calculation formulas having high accuracy. The verification tests have been done in those studies. And the experimental study results show that the calculation formulas are right. From those studies it is found that the seepage control impacts of the cut-off wall are more significant than the infinite deep pervious foundation in controlling the seepage gradients, and the cut-off wall can effectively control seepage-induced damages; and in controlling seepage discharge, the greater the depth of the cut-off wall is, the more significant the effect is, but it needs auxiliary measures to realize reasonable goals in economy and technology. The analysis results of the studies are helpful to further understanding of the seepage control principles of the suspended cut-off wall.