Abstract: To overcome the influence of complex disturbances such as external disturbance and model error on the stable flight of four-rotor UAV, a finite time sliding mode robust control law based on integral filter is proposed. The trajectory model and attitude model of four-rotor UAV were established, and the disturbance observer was designed to accurately estimate the composite disturbance. The finite time sliding mode robust control law was designed for the trajectory model, and the attitude command was solved. The proposed integral filter was used to filter the solved attitude command. The finite time stability control of the four-rotor UAV was realized. The simulation results show that the designed finite time sliding mode robust control law has higher control accuracy, the maximum error of trajectory tracking is only 0.3m, and the designed disturbance observer has better estimation effect on composite disturbance, and the maximum estimation errors is only 0.03 m/s² and 0.02 rad/s², respectively, which realizes the accurate control of four-rotor UAV flight.