Wireless sensor network (WSN) is made of a large number of sensors, which power is limited. The energy management is a hot issue. Owing to the relevance of time and space between sensors, we allow some sensor nodes to be alive and some sensor nodes can be turned off. Mobile sink is powered by gasoline, thus the mobile distance is limited. Therefore, we propose CMSLM (Constrained mobile of sink lifetime maximum) algorithm. Firstly, we select as little as possible mobile sinks under the condition of limited mobile distance for mobile sink. Secondly, we construct balanced tree by the maximum flow, to maximize the WSN lifetime. The experiment simulation shows that the number of dead sensors of CMSLM algorithm is less than SRP-MS.