Abstract: There is always strong tube wave in VSP data，and the current method of tube wave suppression are mainly the median filtering and F-K filtering.Since statistical effects of median filtering and false-frequency of F-K，it is difficult to achieve the desired effect.Based on the time-frequency difference between tube wave and effective signal，the improved generalized S transform(with variable width Gaussian window with the width in proportion to the frequency.When in low-frequency,time window is narrow and time resolution high.When in high-frequency,time window is wide and frequency resolution high) is used to isolate and suppress the noise.Theory and the actual data show that absorption attenuation theory which is based on the tube wave suppression has improved the signal，and achieves satisfied results.

Key words: VSP, median filtering, F-K filtering, S transform, tube wave suppression