This paper focuses on the attitude tracking control problem of spacecraft formation flying under unmeasured angular velocity and saturation input.By combining the unknown saturation effect with the external disturbance into a compounded disturbance,a novel finite-time observer was designed to estimate the angular velocity and compounded disturbance.Based on which,a finite-time sliding-mode cooperative control protocol was proposed.The stability of the system was verified theoretically by constructing an appropriate Lyapunov function.Simulation result shows that the method can implement accurate estimation and cooperative control to the attitude in limited time.