Abstract: Single-time-window synthetic seismograms has been widely used in the past in the seismic survey in the South Yellow Sea. Reflection coefficients was picked out from logging curves and convoluted with theoretical wavelets, so the frequencies for the shallow and deep layers are different, leading to the poor match of the synthetic seismograms to the real seismic profiles. This paper proposes a method to extract seismic wavelet from multi-time-window synthetic seismograms followed by spectrum analysis. Since the wavelet frequency and waveform are different in the shallow and deep strata, time delay is considered, and the results of seismic wavelet are applied to the multi-time-window synthetic seismograms. Multi-time-window synthetic seismograms has advantage of the match degree of synthetic seismograms and seismic wave group and the resolution,comparing with the previous single-time-window synthetic seismograms.