In the light of the shortcomings that particle swarm optimization (PSO) algorithm is poor in locally searching ability in the process of optimization, and/or is slow in speed of convergence in later period, a sequential quadratic programming (SQP) integrated particle swarm optimization algorithm (PSOSQP) is presented. The proposed method not only keeps the characteristics of globally converging of PSO, but also compensates SQP for the effective local search ability, and simultaneously obtains the global optimal result quickly. The method applied to the classic test function can get the optimal solution of high precision. An optimization design of structural reliability for gear reducer is made，and its mathematical model is built up based on PSOSQP. The results show that this method is reasonable and effective in solving the problems of reliability optimal design．