The multi-point location of the airport scene uses the arrival time difference of the mode-s signal to realize the target location. Aiming at the problem that the mode-s signal is susceptible to the internal nonlinear influence of the receiving system and the complex electromagnetic interference of the airport, the method of restoring the distortion of the mode-s signal is studied. According to the spectrum characteristics of mode-s signal and the characteristics of the weak nonlinear memory system of the receiving base station, the Volterra series is simplified, and the ability of the key kernel function of Volterra series to represent the nonlinear distortion of mode-s signal is reduced. The distortion recovery model of mode-s signal is obtained. The simulation results show that the 3-order simplified Volterra series model can recover the pre-distorted waveforms of the leading pulses of 15 dB and0 dB mode-s signals, and the errors are only 2.23% and 12.59%. The model meets certain applicability, anti-interference and stability in typical application environment, which provides a basis for accurate extraction of arrival time stamps.