Aiming at the problem that UAV needs to avoid obstacles in the process of automatic target tracking, a route planning algorithm is designed, which combines tracking guidance law with improved artificial potential field method. The artificial potential field method was improved adaptively, and the dynamic model of UAV was established.The design method of the constant range tracking guidance law was described, and the constant range tracking guidance law and the artificial potential field method were combined by weighted summation and kinematic constraints. The simulation results show that the strategy is effective and feasible.