Abstract: The main purpose of pre-stack seismic inversion lies in getting elastic parameters of underground media and then making liquid identification and reservoir description.In this paper the authors tried to eliminate the inherent trouble that long offset seismic data could not be used efficiently when the approximate Zoeppritz equation is adopted.The authors start with the Zoeppritz equation of P-wave and S-wave velocity and obtain the Zoeppritz equation of compressional and shear modulus.Then,with the new Zoeppritz equation,the authors start the direct compressional and shear modulus inversion based on the generalized linear inversion theory and apply the means to seismic data with all angles.Model and practical test shows that the method is stable and reasonable in obtaining the compressional and shear modulus,and can reduce the cumulative error which is caused by the common elastic inversion method.The result obtained by the authors provides good data basis for the liquid detection and identification.