Abstract: Complex resistivity and polarizability are important parameters in electromagnetic exploration to describe the electrical properties of underground reservoir rocks. To investigate the variations of complex resistivity and polarizability in fluid-saturated tight sandstone reservoirs, complex resistivity measurement was conducted at different temperatures and pressures using outcrop and core samples from a gas field in southwestern China. Based on the experimental results, we establish an induced polarization (IP) petrophysical model for tight sandstones in the study area and analyzed the variations of complex resistivity and polarizability with porosity and gas saturation. The results show that both complex resistivity and polarizability increase with gas saturation; in the context of equal petrophysical properties, resistivity is more sensitive to gas saturation than polarization; resistivity is more easily affected by reservoir petrophysical properties than polarization. The research results lay the foundation for the joint electromagnetic and seismic prediction of reservoir fluid properties.