The attitude control system of a flapping-wing flying robot plays an important role in the precise orientation and tracking of the robot.In this paper,the modeling of a bird-like micro flapping-wing system is introduced,and the design of a sliding mode controller based on an Extended State Observer (ESO) is described.The main design difficulties are the control law and the adaptive law for the attitude control system.To address this problem,a sliding mode adaptive extended state observer algorithm is proposed.Firstly,a new extended state approximation method is used to estimate the final output as a disturbance state.Then,a sliding mode observer with good robustness to the model approximation error and external disturbance is used to estimate the system state.Compared with traditional algorithms,this method is not only suitable for more general cases,but also effectively reduces the influence of the approximation error and interference.Next,the simulation and experiment example is given to illustrate the implementation process.The results show that the algorithm can effectively estimate the state of the attitude control system of the flapping-wing flying robot,and further guarantee the robustness of the model regarding error and external disturbance.