Abstract: A soy protein-polyacrylamide composite salt(SPI-PAAm/ZnCl₂-LiCl) anti-freezing gel electrolyte with antifreeze performance was prepared using soybean protein(SPI), acrylamide(AAm), ZnCl₂ and LiCl as raw materials, and it was applied to hybrid capacitors for the investigation of the electrochemical performance of hybrid capacitor at low temperature. The results of research showed that the addition of ZnCl₂ and LiCl broke the hydrogen bonds among the water molecules in the gel electrolyte, and endowed the gel electrolyte with excellent low temperature ionic conductivity and good low temperature mechanical properties. When the molar ratio of ZnCl₂ to LiCl was 5∶KG-*912, the performance of antifreeze gel electrolyte was the best. At -70 ℃, the anti-freezing gel electrolyte could maintain structural integrity after 100 tensile cycles under 100% strain, the stress retention rate was more than 65%, the plastic deformation rate was less than 25% and the energy loss coefficient was less than 0.35. The hybrid capacitor based on this anti-freezing gel electrolyte exhibited good electrochemical performance at low temperature, and could work normally at -80 ℃. At low temperature, the energy density was concentrated in the range of 50-200 Wh/kg, and the power density was concentrated in the range of 1 000-30 000 W/kg. Even at -70 ℃, the power density of the hybrid capacitor was nearly 1 000 W/kg and the energy density was more than 10 Wh/kg. Meanwhile, the capacitance retention rate of the hybrid capacitor was more than 94% after 5 000 cyclic charge and discharge at -70 ℃, indicating the excellent cycling performance.