In this paper, particle swarm optimization algorithm is used for trajectory optimization of industrial robotic manipulators. Trigonometric splines are used as trajectory optimization algorithm. Trigonometric splines can provide smooth trajectory and continuous jerk at only third derivative of position compared with higher order polynomials and cubic splines. Minimum continuous jerk reduces vibration at the joints that extends mechanism lifespan and provides trajectory tracking with minimal error. Particle Swarm Optimization algorithm (PSO) is used as optimization algorithm due to its easy implementation and successful optimization performance. A sample trajectory is performed for PUMA 560 robot in order to test the proposed method and optimization results are given as graphs.