Abstract：Starting from the approximation of power series of P-SV converted wave reflection coefficient，the paper gave the approximations of P-SV converted wave reflection coefficient represented by multi-composition of different parameters and explored the theory and methods using these approximations for AVO weighted stack parameters inversion. The results of the weighted stack inversion indifferent theoretical models showed that the larger errors existed in directly inversive velocity,densityand wave impedance of P-and S-wave when using P-SV converted wave AVO for weighted stack inversion;on the contrary, direct inversion modulus Δμ/μ and fluid factorΔ(μ p)/(μ p) of shear not on1y has high precision but also has stable inversive results，being adaptable to AVO parameters inversion of P-SV converted wave and multi-wave.
