Concerning the load imbalance of nodes in Wireless Sensor Network (WSN), a new multi-slot allocation data transmission algorithm was proposed based on dynamic tree topology. The data trasimission mode and slot allocation were analyzed by a tree link model at first. Then the node performed frame slot allocation based on slot requirements by using the relationship between parent and offspring in the tree topology;and a sequence mode for reception slot and a sequence mode for transmission slot were given, so as to allow the node to be more ordered and receive packets sent by the other nodes in less interference channel, reducing waste of time slot and improving utilization efficiency of channel slot. Compared with life cycle extension algorithm for WSN based on data transmission optimization and reliable data transmission algorithm based on energy awareness and time slot allocation, the simulation results show that the network energy efficiency of the proposed algorithm increases by 42.8% and 51.7% respectively, and the average lifetime of the nodes extends by 1.7% and 37.5% respectively, the energy efficiency and network life cycle are optimized.