The biggest problem for the development of wireless sensor network is the limited energy of sensor. It has always been the research focus of routing protocol on wireless sensor network to effectively reduce node energy consumption, to balance energy consumption of the entire network, and to extend the life cycle of sensor network. By directing at problems of LEACH protocol such as uneven distribution of cluster heads, unreasonable cluster head selection and rotation mechanism, and single-hop communication of cluster heads with base station, this paper proposes an improved algorithm LEACH-DT (LEACH- Dynamic threshold) of LEACH protocol. In the first round of this algorithm, the base station will calculate the optimal number of cluster heads and select cluster head nodes according to node energy and node density. When the energy of cluster head is smaller than the energy threshold, rotation of cluster head nodes will be conducted, and data of cluster head will be transferred to the base station in a multi-hop way through the shortest path tree. According to the simulation experiment, the improved LEACH-DT algorithm has balanced energy consumption of various nodes in network, reduced average energy consumption of the nodes, postponed death time of the first node in network, extended the life time of network, and increased the network throughput.