Abstract: The normal moveout correction(NMO) is an important step in seismic data processing. After the digital NMO correction, the events with large ratio of offset and reflection depth have the phenomenon of stretch and distortion. NMO mute causes the loss of effective data with large ratio of offset and reflection depth. Conclusions can be drawn through theoretical calculation. If the events are overlapped, they have the maximum stretch value. After the correction, the events having the appearance of distortion and the number will be increased. Otherwise, the events will show a fat wave shape, the dominant frequency will decrease, the frequency band will be narrow and the amplitude larger. Therefore, it's significant to study the non-stretch correction method. With the method, the signal-noise ratio and resolution of seismic data can be improved. Using the spectrum based moveout method, the information of large offset and effective stacking times increase. The events will be more continuous and become easier to recognize and trace. This method is suitable for marine seismic data processing.