Abstract: It's an important issue to evaluate the seal ability of a fault in exploration,exploitation and reservoir management in oil & gas industry.Nowadays,scholars at home and abroad are apt to semi quantitatively and quantitatively evaluate the conductibility and seal ability of afault,and evaluate it in a fashion of multi-dimensionally with its evolution history.The transverse and longit udinal wave velocities of rock are important parameters in evaluation of stratum and seismic exploration and petroleum geology.Attention has been paid to acoustic attenuation in early time.But,it has been lacking an effective method due to characteristics of gas source faults.Therefore,we try to employ change of the sonic velocity and attenuation to differentiate the type of gas source faults and their roles in the deposition.