High ionic conductivity and superior interfacial stability of solid electrolytes at the electrodes are cru-cial factors for high-performance all-solid-state sodium batteries.Herein,a composite solid electrolyte Na3PS4-polyethylene oxide is synthesized by the solution-phase reaction method with an improved ionic conductivity up to 9.4×10-5 S/cm at room temperature.Moreover,polyethylene oxide polymer layer is wrapped homogeneously on the surface of Na3PS4 particles,which could effectively avoid the direct con-tact between Na3PS4 electrolyte and sodium metal,thus alleviate their side reactions.We demonstrate that all-solid-state battery SnS2/Na with the composite solid electrolyte Na3PS4-polyethylene oxide deliv-ers an enhanced electrochemical performance with 230 mAh/g after 40 cycles.