In order to solve the contradiction between the features of the large scale, wide distribution and limited bandwidth for wireless sensor networks (WSNs) and upper bound of the reliable and realtime data communication, a routing communication model based on minimum traffic is proposed in this paper. Using the traffic balance between the received data and the transmitted data in WSN node as an entry point and considering the constraint condition for WSN communication and the realtime requirement of data transmission, the routing communication model based on the minimum traffic is established for WSN communication applied to smart distribution grid. Hamilton function of WSNs communication model applied in smart distribution grid is constructed by using the method of Pontryagin’s extreme values. Utilizing uniqueness of extreme existence and combining with necessity, the proposed method can judge whether the wireless sensor nodes in the optimal path. The process of solving the optimal control model is also given. The communication performance including delay time, network energy consumption, transmission capacity and error rate of transmission data is tested for the proposed routing method. The results show that the proposed model can fully meet the requirement of smart distribution grid communication.