As the number of wireless communication users grows, the macro cells are overloaded, and the edge users are gradually intensified by the interference of the neighboring micro-cell, resulting in a decrease in communication service quality of the entire cell. In order to solve these problems, the Particle Swarm Optimization(PSO) algorithm and Cell Range Expansion(CRE) technology are combined to dynamically adjust the service area of Femto Base Station(FBS) and find out the optimal offset value of CRE, so as to relieve the load pressure of high hotspot area of Macro Base Station(MBS) and improve the overage transmission rate of system users for the two-layer wireless heterogeneous network. The simulation results show that the number of macro cell users, who use the dynamic CRE bias selection, is decreased by nearly 10%, that is, uninstalling some macro users to access the micro-cell, realizing the effect of unloading macro users for the macro cell. And the Signal to Interference plus Noise Ratio(SINR) of the micro-cell edge user is increased by about 2 dB. The average transmission rate of system users is increased, and the communication service quality of the whole community is greatly improved.