The complex electromagnetic environment around the high-voltage transmission line affects the steady operation of the patrol UAV directly, and further affects the evaluation results of the patrol inspection by ground operators. In order to ensure the reliability of UAV in the harsh electromagnetic environment, the electromagnetic environment around UAV is simulated. Based on the coupling path of interference electromagnetic wave, the electric field coupling model and the magnetic field coupling model are constructed respectively. The coupling between the internal electrical structure of UAV and the high-voltage transmission line is analyzed to determine the disturbed target. Based on the generation of the interference source and the electromagnetic coupling path, the electromagnetic compatibility optimization of the UAV is carried out. The electromagnetic shielding is used to weaken the electromagnetic interference to the internal electrical structure and sensitive components of the UAV, so that the electromagnetic compatibility performance of the UAV is improved, and the operation stability of the patrol UAV is guaranteed.