Abstract: In this paper, the medium parameters of the elastic wave equation ininhomogeneous medium are rewritten by introducing the referential variables and theperturbational variables, and the wave equation whose sources are the mediumparameter perturbational term in homogeneous medtam is obtained By usingthe Green function theory, the integral equation of the perturbational parmeters isobtained. Then the displacement field in homogeneous medium is considered the resultof the first iteration, and the displacement fisld is solved by this integral equation.When the perturbations of medium paranteters are about 50 percent, this method cansolve the displacement ficld effectirely. From the analysis of the numerical results, thecharacteristics of wave field in inhomogeneous medium are obtained. The resultsconform with the local principles of wave. function in inhomogeneous medium.