The multi-parameter inversion of elastic wave equation in a half-space within the Born approximation is studied. A method of simultaneously reconstructing the configurations of the density and Lam parameters of the medium was presented by use of a wideband measuring schemes in which transmitters and receivers scan over the half-space surface. It is shown that the reflected waves generated by horizontal and vertical pulses on the surface can be decomposed into P→P、P→S、S→P and S→S types of scattering components. As is expected, these components contain enough information for desired restruction. From them the density and two Lam parameters are determined explicitly, and the results obtained have the form of filtered back-propagation as in the acoustic diffraction tomography.