Abstract: The tight sandstone reservoirs of the Xu-2 Member of the Xujiahe Formation in Hexingchang area, the western Sichuan Basin, are characterized by ultra-low porosity and ultra-low permeability. To clarify their electrical responses during nitrogen displacement, this study deals with ten tight sandstone core samples tested using a high-temperature and high-pressure core displacement system with simultaneous resistivity and frequency-domain induced polarization (FDIP) measurements, under a constant nitrogen injection rate of 1 mL/min, temperatures of 100 and 120 °C, and confining pressures of 60 and 74 MPa, with core resistivity and FDIP recorded in real time. The dominant controls on electrical variations are established by analyzing the effects of temperature, confining pressure, and porosity on resistivity and FDIP responses. The results show that both resistivity and FDIP responses generally exhibit a four-stage evolution pattern: initial stability, rapid increase, slow change, and final stabilization. Higher temperature improves nitrogen displacement efficiency, reduces residual water saturation, and increases resistivity variation. Confining pressure has a relatively weak effect on electrical responses and mainly acts indirectly by regulating water saturation in conjunction with temperature. FDIP responses are strongly controlled by water saturation and most significant near an intermediate water saturation. Cores with better reservoir properties display more pronounced resistivity and FDIP variations with changing temperature and pressure, while medium- and high-quality reservoirs show stronger FDIP responses than poor reservoirs at 100 °C. These results indicate that nitrogen displacement affects rock electrical properties primarily by altering water saturation, and the underlying mechanism can be attributed to the reconstruction of conductive networks caused by saturation changes. This study provides experimental support for electrical interpretation and fluid identification in tight sandstone reservoirs under high-temperature and high-pressure conditions, and highlights the importance of accounting for the dynamic evolution of electrical parameters during displacement when applying electrical methods in practice.