Abstract: Based on the theory of fracture mechanism applied in finite element method, friction characteristics of the horizontal cracks in concrete gravity dam body were simulated and analyzed, and the mechanical properties of crack tip and variation laws of dam displacement and stress state with different friction coefficients were concluded in detail. The results showed that, regardless of dam crack or the whole dam, there were abrupt changes of the mechanical properties of dam and crack in some interval, and it was important to pay attention to the phenomena in dam safety monitoring. The study in this paper can provide guide in the monitoring of concrete dams with some cracks during operation, and provide a basis for dam rehabilitation.