To solve the problem that the traditional inversion of dispersion particle size distribution with the method of dynamic light scattering requires prior knowledge or constraints for the solution, a new inversion algorithm of dynamic light scattering based on singular value decomposition was proposed. Firstly, the Hankel matrix H with the intensity autocorrelation data was constructed. Secondly, the singular value decomposition of H was calculated. Thirdly, the rank of the reconstruction matrix with the singular value of H was determined. Finally, the characteristic value decomposition with the new matrix was calculated, and then the particle size distribution was obtained. The experiment was carried out using two and three different sized particles dispersion respectively. The results show that, in the measuring with two different size particles, the new method can achieve good results without any prior knowledge or constraints for the solution; it is not so good in the measuring with three different size particles and can distinguish three different size particles, but the results have large deviation, especially for the smaller particles. Through the analysis of the experiment, the main reason was found that the small particles scattered light is easily blocked by large particles.