The invention provides an undulatory sea surface ghost reflection suppression method and device. The undulatory sea surface ghost reflection suppression method comprises that based on an undulatory sea surface reflection coefficient calculation formula, the angular frequency, the wave number, the ocean wave height and the seawater speed which correspond to the obtained seismic data in a frequency-wavenumber domain are calculated to obtain a reflection coefficient; a white noise coefficient is obtained by calculating the angular frequency corresponding to the seismic data in the frequency-wavenumber domain; a ghost reflection suppression operator, of the frequency-wavenumber domain, corresponding to preset towing cable scanning depth is obtained by calculating the reflection coefficient and the white noise coefficient; frequency-wavenumber domain suppression data is obtained by means of the suppression operator; then the frequency-wavenumber domain suppression data is converted into time-space domain suppression data; the time-space domain suppression data is divided by a preset time window interval; the sum of absolute values of frequency domain data corresponding to the towing cable scanning depth in the same time window is worked out; and the time-space domain suppression data corresponding to the minimum sum of the absolute values serves as seismic data of the corresponding time window after ghost reflection suppression. According to the invention, undulatory sea surface ghost reflection can be effectively suppressed.