In order to prolong the lifetime

reduce the energy consumption

and balance the network load effectively

a dynamic alliance model and its corresponding algorithm of task allocation in wireless sensor network（WSN） were proposed.This method described a cost function according to the execution time

energy consumption and load balance.Particle swarm optimization was used to optimize task allocation.Meanwhile

a mutation operator that could effectively improve the algorithm’s ability on global search and maintained population diversity was also introduced.Simulation results show that the proposed algorithm provides a good balance of local solutions and global exploration

which results in a great decrease of execution time and a steady balance of network load.