The influence of change of temperature on the safety coefficient of stability of dam with different rigidities is studied by use of a program for the 3D finite element method(FEM) of strength reduction considering the coupling of temperature and stress fields.Through simulation with the program,the following result is gotten: the increase of dam's temperature can make the safety coefficient of dam stability decrease if the elastic module of dam is rather small,but the increase of dam's temperature can make it decreases if the module is rather big.