Reasonable deploy the electric capacity of hybrid wind-solar-battery power system can reduce the energy waste and down-regulate the system cost as well as improve the reliability of power supply through utilizing the complementary characteristic of wind-solar. A capacity optimization method is realized based on the amelioration of particle swarm optimization for hybrid wind-solar-battery power system. Above all, established the calculation model of system costs according to the consideration of whole life cycle, and ameliorated the particle swarm optimization utilizing nonlinear dynamic improved inertial weight strategy in the limiting indexes of low cost, low loss of load probability and low energy wastage rate.Then made optimized configuration of system capacity and finished the simulation calculation of examples in MATLAB. The results show that this configuration scheme of capacity after improve the arithmetic can reduce the system cost and decrease the loss of load probability.