Addressing the trajectory tracking problem of a quadrotor UAV, a command filter backstepping control strategy based on predefined time is proposed to mitigate the impact of model uncertainties and unknown external disturbances on system stability. Firstly, a predefined-time disturbance observer is designed to accurately estimate the system uncertainties and unknown external disturbances in real-time. Secondly, to effectively alleviate the "differential explosion" issue in the backstepping control strategy, a predefined-time command filter is designed. Based on this, position and attitude controllers are further designed using the backstepping method, enhancing the system′s control accuracy and response speed. Finally, the Lyapunov theory is employed to verify the stability of the proposed control strategy. Simulation experiments validate the effectiveness and superiority of the proposed control strategy.