In this paper, formation control of a team of unmanned aerial vehicles (UAVs) for a maneuver flight task has been considered. During the formation maneuver flight, the UAVs subject to input saturation. In order to solve the control problem, saturation was treated as a kind of disturbance. For this kind of disturbance, we propose an exponential convergence observer to obtain its estimated value. Then new attitude subsystem control laws which enable formation to turn smoothly have been designed based on exponential observer. The simulation results demonstrate the effectiveness and robustness of the proposed control laws.