This paper presents a study of optimal control design for a nonlinear dynamical system with the multi-objective particle swarm optimization(MOPSO) algorithm. The multi-objective optimal design of the nonlinear control involves 4 design parameters and 6 objective functions. The multiobjective particle swarm optimization algorithm finds the Pareto set and Pareto front efficiently. Numerical simulation and experiment validation are done on the rotary inverted pendulum system to verify this tuning technique. Numerical and experimental results show that the MOPSO tuning technique is quite effective. This paper presents a study of optimal control design for a nonlinear dynamical system with the multi-objective particle swarm optimization(MOPSO) algorithm. The multi-objective optimal design of the nonlinear control involves 4 design parameters and 6 objective functions. The multiobjective particle swarm optimization algorithm finds the Pareto set and Pareto front efficiently. Numerical simulation and experiment validation are done on the rotary inverted pendulum system to verify this tuning technique. Numerical and experimental results show that the MOPSO tuning technique is quite effective.