Abstract: The tight sandstone gas reservoir has the characteristics of low porosity and low permeability,complex pore structure and strong heterogeneity,which makes the reservoir evaluation difficult. The conventional methods based on volume model in medium-high porosity and permeability reservoir is not suitable for this kind of reservoir due to much more contribution of sandstone framework to logging. Two methods of gas-bearing identification were optimized based on conventional loggings: apparent elastic modulus coefficient method and three porosity ratio method. The combination of the two methods can effectively identify gas layers. According to reservoir characteristics and relationship analysis of rock electricity and response, the porosity,permeability and saturation of tight sandstone reservoir were calculated by using neutron-density weighted average,median grain size linear regression and parameter variable Archie's equation methods,completing the high precision quantitative evaluation of tight sandstone gas reservoir in the southern Yanchuan block. These methods are also applicable to evaluate tight sandstone gas reservoir in other area.