In order to achieve close tracking of ground targets by unmanned aerial vehicle (UAV), a guidance method based on differential geometry for UAV over-flight ground tracking is proposed in this paper. Firstly, the mathematical model of the UAV ground tracking target is built, and the mathematical relationship is analyzed. The guidance law of the UAV is designed to track the ground target, and the stability analysis is completed. Finally, the simulations are carried out for targets in different movement states respectively. The simulation results show that the method can effectively tracks all kinds of ground targets and has good tracking performance.