With the improvement of the agricultural automation level, Multi-rotor plant protection UAV is widely used in agricultural production. The multirotor plant protection UAV is the research object in this paper. Based on the AYSYS Workbench software, researches are focused on the static analysis and modal analysis on the rotor of the multirotor plant protection UAV. The result of static analysis indicates that the dangerous areas of the rotor are mostly in the root of blades, and the maximum stress is less than the allowable stress, which can meet the stiffness and strength requirements. The result of modal analysis indicates that it will not cause resonance, which complies with the design requirements because the avoidance rate of rotor natural frequencies and excited frequencies are greater than 15%. Through the finite element analysis of the rotor structure by using ANSYS Workbench software, it provides a theoretical basis for the further research of multi-rotor plant protection UAV in design optimization process.