All-solid-state sodium-ion batteries have been considered as a prospective choice for energy storage systems due to their low cost and high safety comparing to lithium-ion batteries. In this work, we studied about an air-stable NASICON-type sodium-ion solid electrolyte (Na3Zr2Si2PO12, NZSP). The ionic conductivity was improved by Ca doping. After optimization, the sodium-ion conductivity increased from 1.4 × 10-4 S cm-1 to 1.8 × 10-4 S cm-1 at room temperature, demonstrating that the modified NASICON-type electrolytes have the potential of developing low-cost and high-safety energy storage systems. In order to reduce the contact resistance between solid electrolytes and electrodes, we mix Ca-doped NASICON (NCZSP) and Polyethylene oxide (PEO) to form composite solid electrolytes. Then assemble an all-solid-state NIB with Na(NiCuMnFeTi)0.2O2 high-entropy layered oxide as cathode and Na as anode. The full cell exhibited excellent cyclic stability, suggesting that this composite material is a very promising solid-state sodium-ion electrolyte.