Based on AVO theory, zero-offset (or small offset) section can be approximated as function of acoustic wave impedance AI, which is related to density and P wave velocity. Elastic impedance is the promotion of acoustic wave impedance, and it is the function of P wave velocity, S wave velocity, density and angle of incidence. Elastic impedance can provide not only wave impedance information, but also P/S wave velocity ratio, Poisson's ratio which can reflect reservoir information including physical properties and fluids properties. Pre-stack inversion could provide more reliable information about reservoir distribution and oil-gas possibility, greatly improve precision and accuracy of reservoir prediction, and enhanced success rate of well position plan.