Abstract: For static strip distribution characteristic of wireless sensor networks nodes used in underground pressure monitoring system, the minimum hop count routing protocol was taken as a research object and improved in route creation phase, data transfer phase and maintenance update phase. An improved routing protocol named the minimum hop count based on node energy classification was put forward. The improved routing protocol reduces control group and redundancy of data transmission path by grading the node energy. The simulation result show that the improved routing protocol has obvious advantages in extending life period of network, reducing average end delay of data packet and reducing percentage of control packets over the traditional directed diffusion routing protocol and the minimum hop count routing protocol.