The insertion and removal of tasks in the task priority hierarchy always cause the problem of the joint velocity discontinuity. In this paper, an iteratively successive projection multi-task priority method is proposed based on the iteratively successive projection mechanism. Based on Lyapunov’s stability theory, the stability of the proposed method is verified under the condition that iteration times tend to infinity. Taking the obstacle avoidance task as the primary task and the trajectory tracking task as the secondary task, the performance of the iteratively successive projection multi-task priority method is simulated and compared with the traditional augmented projection multi-task priority method. Simulation results show that obstacle avoidance tasks are inserted into the priority hierarchy when approaching obstacles, and the iteratively successive projection multi-task priority method can ensure the joint velocity continuity. In addition, within the ability of redundancy, the end trajectory tracking task is performed as much as possible, and the convergence of the tracking error is guaranteed.