Clustering algorithm provides an effective way to save energy for the large-scale Wireless Sensor Network (WSN) remote monitoring system. Cluster-heads communicate data to the base-station through the multihop routing way. The cluster-heads closer to the base-station may be over-loaded due to transmitting lots of other cluster-heads data, which may consume all the energy and be early dead so as to cause the entire networks partition. Concerning the uneven energy consumption in wireless sensor networks clustering algorithm, an uneven clustering algorithm based on Particle Swarm Optimization (PSO) was proposed. By using the PSO algorithm, PSO-UCA partitioned all nodes into clusters of unequal size, which the clusters closer to the base-station have smaller size. Thus, the cluster-heads closer to the base-station can preserve more energy for the inter-cluster relay traffic. The simulation results demonstrate that, compared with LEACH algorithm, the clustering algorithm can prolong the network lifetime by 30%.