Abstract: In low porosity and low permeability sandstone reservoirs, the development of micropores bring some difficulties to the evaluation of rock conductivity and petrophysical parameters. Taking Block A in Sulige gas field as an example, the micropore limit in this field is redetermined as 0.15 μm by means of the principle of balanced dynamics and resistance, and the "non?Archie" phenomenon is explained by numerical simulation and mathematical statistics. The studies show that the pore type determines proportion of micropores, and the big?ger the porosity, the smaller the proportion of micropores; with the proportion of micropores increasing, the permeability is obviously decreased; the sandstone reservoir with low porosity and permeability is characterized by significantly increamental neutron porosity and small changes of the density and the interval transit time, and with the increase of clay content, the irreducible water saturation increases,the conductive network develops, conductivity enhances, and the resistivity decreases. Therefore, the micropores occurrence is the main reason for the low resistivity phenomenon appeared in the low porosity and low permeability reservoirs in this area