Load balancing algorithm for heterogeneous wireless networks based on utility function is proposed in this paper. Through timing measurements of network parameters,the algorithm firstly gets the utility function of each performance index,and secondly deals with the indexes by normalization and weighting process,then selects the busiest RAN and lightest RAN,and also selects the low QOS utility terminal,finally achieves load balance by transferring terminal. Simulation results show that the proposed algorithm can effectively improve network throughput and reduce network congestion rate and timedelay.