Abstract: In order to overcome the conflicts among various objectives in the optimization design of power converters, a multi-objective optimization model of power converters with efficiency, physical size (volume, weight and area) and cost is established as optimization objectives in the paper. The model is solved by using multi-objective particle swarm optimization (MOPSO) algorithm and decision makers can find different compromise optimal solutions in the final set of optimal solutions provided. Vienna rectifier and Buck converter are taken as research objects. Their respective multi-objective optimization functions are established, and introduced into the device database, and the MOPSO algorithm is implemented on Matlab. Simulation results show that the MOPSO algorithm is feasible, coverage and convergence, and it can converge to the optimal solution set in a relatively short time.