Abstract: To ensure the flight safety under the condition of the wing damage in the aircraft, a new online fault diagnosis method is proposed based on the nonlinear aerodynamic model of the wing damage. Firstly, according to the input and output characteristics of the aircraft, the aerodynamic derivatives can be identified online using the recursive least squares algorithm with a forgetting factor, and the wing damage model can be established as the aerodynamic derivatives are substituted into the equation of the aircraft motion. Secondly, the fault diagnosis approach is proposed based on the multi-model algorithm and the central difference Kalman filter algorithm, and the adaptive capacity of the central difference Kalman filter algorithm can be strengthened as the sampling points are updated online using the strategy of a strong tracking filter. Lastly, in the presence of various wing damage faults, the simulation results indicate that the proposed algorithm can not only improve the experiment effciency but also ensure the fault coverage as compared with other algorithms.