Based on the nonlinear contact theory, combined with finite element analysis method ,this paper made sensitivity analysis of counter-arched slab whose chord length is 130m and which has more than 9blocks. It also studied the influence on the stability of the counter-arched slab under different anchor level and way, different reverse arch curvature and key groove. And it draw the following conclusion that anchor bar plays key role in counter-arched slab''s overall stability; uniform anchor bar distribution is the most suitable way for the overall stability and intermediate plate without anchor bar can be selected as a good way; for reverse- arch-shaped water cushion pond whose chord length up to 130m, the arch central angle about 74° is reasonable; the local stability has increased significantly by the influence of key groove.