Abstract: Wireless sensor and actor network (WSAN) has good prospects for application, it is widely used in many fields, such as industry, traffic-transportation and health care. However, its heterogeneity, mobility, energy consumption, topology and other issues will be a challenge to the effective operation of the WSAN. Software Defined Network (SDN) is a new technology that it can configure networks and solve the conflict of rules in the distributed system easily and effectively in a centralized and programmable pattern. In order to improve the communication efficiency and scalability of WSAN, this paper studies the model that applying SDN to the WSAN model. The specific model includes three-layer architecture with a new control plane, the corresponding system entities and strengthened protocol stack. The experimental results show that the architecture of the separation of control and forwarding that SDN has adopted can make the complex network management become simple and convenient.