Fly-by-wire flight control systems provide more advanced flight control and protection functions for aircraft, while the introduction of fly-by-wire flight control increases the probability of system failure caused by complex electronic components. The fly-by-wire flight control surface oscillation fault may affect the aircraft structure load and other aspects. In order to detect and correct the specific control surface oscillation fault, an effective solution is proposed in this paper, so as to detect the control surface oscillation fault in the early stage. The scheme is composed of nonlinear robust observer, wavelet band decomposition and oscillatory fault confirmation. Simulation results show that the scheme has the advantages of low computing resources, short detection period and low fault amplitude detection, and can realize robust monitoring against external interference.