In order to discuss the influence factors for behaviors of construction safety supervision of water conservancy projects, the evolutionarily stable strategy (ESS) of construction safety supervision is analyzed. Using the method of game theory, an evolutionary game model for supervising units and construction contractors is established based on the assumption that both of them have bounded rationality. The results of ESS show that the choices of supervising units are influenced by the degree of supervision cost and reward, error rate of supervision and the possible punishment, and those of construction contractors are influenced by the degree of construction cost and reward and the possible punishment. The ESS of the supervising units and construction contractors is associated with the initial values of various factors. Finally, a numerical simulation for dynamic game between the two sides is performed by using the Matlab software. Some suggestions are put forward for strengthening the construction safety supervision of water conservancy projects in China.