Abstract: In order to research the distribution form of hydrate and occurrence of gas hydrate in Xisha area of quasi three dimensional wave impedance inversion of seismic data. Demonstrates the processing in detail about no Wells impedance inversion: According to the geophysical characteristics of hydrate do zero phase of seismic data processing; According to the characters of seismic data itself, in the work area of multiple tectonic region extraction of seismic wavelet, to ensure the stability of the wavelet to calculate the average wavelet; According to the stacking velocity, by smoothing, filtering, conversion and interpolation to calculate the 3D low frequency model. Finally got the inversion result of clear geological phenomenon, and can be accurate image the distributed area of the hydrate, favor to the comprehensive analysis of the subsequent hydrate research.