Abstract: The sandstone reservoir of Huagang Formation in Structure W in Xihu Sag is characterized by deep burial depth, lateral alteration in lithology, and classified as the low porosity and low permeability reservoir. The analysis of the petrophysical properties in the wells drilled in this area shows that low P-S wave velocity ratio indicates the existence of sandstone reservoirs, low P-S wave velocity ratio and high Poisson dampening factor may indicate high possibility of gas bearing reservoir. Based on the study of AVO modeling and inversion on logging data, it can be concluded that the comprehensive analysis of P-S wave velocity ratio and Poisson damping factor can be used to effectively distinguish low porosity-low permeability reservoir and ultra-low porosity-low permeability reservoir. In addition, the higher accuracy can be expected with the increase of the wavelet frequency.