Strength reserve coefficient method based on nonlinear FEM is adopted to analyze the failure process of gravity dam along the foundation surface. Meanwhile

the influences of elastic modulus ratio of dam to foundation and stress distribution along foundation surface on the failure process and strength reserve coefficient (SRC) are studied. The results indicate that the failure process can fall into four periods: smooth connectivity period

acceleration period

short smooth transition

sharp accelerating failure period. With a constant elastic modulus ratio of dam to foundation

the more uniform the stress distribution is

the greater SRC is. The greater the ratio of stress at dam’s toe to dam’s heel is

the smaller SRC is. When stress distribution along foundation surface is invariable

the variation of elastic modulus ratio does not affect the overall failure feature of the foundation surface and the SRC is in proportion with the elastic modulus ratio. Finally

the true safety degree at the range of 1.5－2.5 is proposed for the failure evaluation of gravity dam along the foundation surface under normal loads.