Optimal allocations of water resources include initial water allocation and water right exchange in the water market. The spontaneous evolution of price competition strategies for completed water markets is analyzed using evolutionary game theory in this paper. This paper also analyzes the evolutionary process of bidding strategy of water supply enterprises and obtains the evolutionary stable strategy. Moreover, the practical significance of this strategy is analyzed and the related stability analysis is conducted. Studies real that the system is stable when water supply enterprises adopt the same strategy, i.e., they all quote a relatively high offer or offer according to the cost. At the same time official mechanism is brought forward to control and accommodate water market price strategy so as to show advantages.