With the development of society and the progress of science and technology, the power system is developing continuously. People are not only pursuing economic benefits, but also paying more attention to other issues like the energy waste and the safety in power system. In this paper, the three objectives of fuel cost, active power loss and voltage quality are selected as optimization objectives. Based on PSO, GA and DE, a multi-objective optimization algorithm CO-PGDEA based on coevolution is proposed. Experiments on standard test functions and IEEE-30 nodes show that the proposed algorithm has better convergence and stability, and is easier to obtain the complete Pareto frontier