Abstract: According to the kinematic constraints of manipulator,a time-optimal 3-5-3 polynomial interpolation trajectory planning algorithm based on particle swarm optimization(PSO) is proposed,which solves the problem that polynomial interpolation based trajectory planning is hard to be optimized by traditional optimization methods for its shortcomings of high order and lack of convex hull property,etc.The characteristics of simple structure and easily adjusted parameters of PSO remedy the defects of polynomial optimization.Searching directly in the optimization space of the target skillfully avoids the mapping between independent and dependent variables,reduces the search dimension and simplifies the computation. In the optimization process,switch control is used between the two fitness functions to make interpolation converge quickly within the kinematic constraints.The comparison between the the algorithm and traditional 3-5-3 spline interpolation on the position,velocity and acceleration of the movement shows that the running time of the algorithm is shorter,and its stability and fluidity are better.