To solve the problem of unstable configuration of multi-UAV formation caused by model biases and external disturbances, an idea of model-compensation control is proposed.Based on this, a model-compensation backstepping controller based on Compensation Function Observer (CFO) is designed and applied to formation cooperative control.The formation cooperative control problem is transformed into a traditional control problem, so as to realize the assembly, flight and shape switching of multi-UAV formation under complex external disturbances.The proposed controller not only retains the global exponential asymptotic stability based on Lyapunov criteria, but also employs a CFO to accurately estimate model biases and disturbances and then compensate for them into the controller, effectively enhancing the anti-disturbance capability of the overall formation system.Finally, the effectiveness of the algorithm is verified by simulation and experiment.