Abstract: To meet the urgent demand for wide-temperature-range adaptability and high safety of energy systems in extreme environments such as deep space exploration, a novel organic-inorganic composite sodium solid electrolyte was designed and prepared in this paper for the construction of high-performance sodium solid-state batteries. Lead methylammonium chloride (MAPbCl₃) with a perovskite structure was used as an inorganic ion conductor, combined with sodium alginate (SA) and multifunctional polymer ETPTA, and a stable and dense composite polymer network was formed through in-situ ultraviolet light-initiated polymerization. This composite electrolyte has a high ionic conductivity of 5.65×10⁻⁴ S·cm⁻¹ and excellent Na⁺ transference number of 0.65 at room temperature, and still maintains stable performance at -20℃. In the assembled NVP | MSE | Na all-solid-state battery, the capacity retention rate is 68.4% after 200 cycles at room temperature and 69.6% after 100 cycles at -20℃, which is significantly better than the traditional physical dispersion system. The research results show that the constructed composite structure has good interface stability and cycling performance at extreme temperatures, providing key material support for future energy storage systems for polar observation and deep space exploration.