In this paper, we address the problem of MAC address assignment in wireless sensor networks. A novel scheme for MAC address assignment is proposed to reduce the overhead. We model the problem from the game theoretical view, prove there exists a mixed strategy Nash equilibrium in the model, and propose a distributed address assign algorithm to achieve the equilibrium, which takes the advantage of the exploitation of spatial address reuse to save energy. Simulation results demonstrate that our algorithm is efficient even for very largescale networks, which makes it a potential candidate for practical applications.