Energy balance of nodes in wireless sensor network is a difficult point. In this paper, analyze the performance of AODV routing protocol applied to the coal mine WSN environment which has less mobile nodes. Base on its characteristic of lacking of energy efficiency and optimal route selection considerations, an improvement of AODV routing protocol is carried out. Route discovery phase of the algorithm use a cost metric routing strategy, according to the energy level of nodes and the quality of links to calculate the routing cost, lower cost routing path will be selected. Between efficient routing and energy balance make an effective trade-off, improve the delivery rate of the network.