The attitude tracking cooperative control problem under directed topology is addressed for a class of Quadrotor Unmanned Aerial Vehicle Formation System (QUAVFS) in the presence of dynamic disturbances and input saturation. Firstly，the attitude dynamic model of QUAVFS is established，and an auxiliary anti-saturation system is constructed to solve the input saturation problem of UAV actuators. Secondly，a finite-time disturbance observer based on the high-order sliding-mode differentiator technique is designed to compensate for time-varying dynamic disturbances. Finally，an attitude tracking cooperative controller for QUAVFS is designed by utilizing the backstepping method and the multi-agent consensus theory，and the bounded stability of the closed-loop system is demonstrated via Lyapunov stability theory. The simulation results illustrate the feasibility and effectiveness of the proposed scheme.