In this paper, different conditions of pick-and-place trajectory are analyzed, and on this basis, the dynamic picking algorithm for the workpieces on the conveyor belt is proposed by using the Ferrari’s method. Then, the trajectory planning algorithm of sorting multiple types of workpieces is proposed by analyzing the trajectory planning model of two types of workpieces. The workpiece to be sorted is determined first, and then will be picked up at the picking point calculated by dynamic picking algorithm. Experiments show that the dynamic picking algorithm is accurate and fast; does not need to set the initial value and is suitable for practical engineering applications. And the algorithm of trajectory planning for multiple types of workpieces has high accuracy and stability.