An improved artificial potential field (IAPF) algorithm is proposed in this paper to promote the path planning characteristics of autonomous underwater vehicle (AUV). There are two critical problems restricting the application of obstacle avoidance path planning for the artificial potential field (APF) algorithm, one is the local minima and the other is the target unreachability problem. Therefore, the distance between the target and the AUV in attractive field is introduced into the repulsive potential field to modify the repulsive force so as to solve the problem of target unreachability. Moreover, an additional force is added to the resultant force to break the equilibrium when the local minima situation occurs. Ultimately, the simulation experiment validates that the improved artificial potential field method is an efficient way to realize the path planning for AUV in 3D space.