Based on P systems, this paper proposes a new multi-objective optimization algorithm (PMOA). Similar to P systems,PMOA has a cell-like structure. The structure is dynamic and its membranes merge and divide at different stages. The key rule of a membrane is the communication rule which is derived from P systems. Mutation rules are important for the algorithm, which has different ranges of mutation in different membranes. The cooperation of the two rules contributes to the diversity of the population, the conquest of the multimodality of objective function and the convergence of algorithm. Moreover, the unique structure divides the whole population into several subpopulations, which decreases the computational complexity. Almost a dozen popular algorithms are compared using several test problems. Simulation results illustrate that the PMOA has the best performance. Its solutions are closer to the true Pareto-optimal front and distributed well. Moreover, it converges fast.