To resolve the problems that the traditional algorithm of particle size distribution inversion has no good convergence accuracy and is apt to be trapped in local optima,a stochastic particle swarm optimizer(SPSO) algorithm,which is based on laser transmitting model,is proposed to estimate the size distribution of particles.The novel SPSO-based method is proved to be available to retrieve the reasonable particle size distribution such as R-R distribution,normal distribution and lognormal distribution for the independent model.The algorithm is simple,easy to implement and unnecessary the optimization objective function′s continuity and differentiability.Additionally,It has strong robustness and adaptation to improve the reliability and sensitivity of the inversion of particle size distribution.