Solid-state　electrolytes　(SEs)　have　attracted　overwhelming　attention　as　a　promising　alternative　to　traditional　organic　liquid　electrolytes　(OLEs)　for　high-energy-density　sodium-metal　batteries　(SMBs),　owing　to　their　intrinsic　incombustibility,　wider　electrochemical　stability　window　(ESW),　and　better　thermal　stability.　Among　various　kinds　of　SEs,　inorganic　solid-state　electrolytes　(ISEs)　stand　out　because　of　their　high　ionic　conductivity,　excellent　oxidative　stability,　and　good　mechanical　strength,　rendering　potential　utilization　in　safe　and　dendrite-free　SMBs　at　room　temperature.　However,　the　development　of　Na-ion　ISEs　still　remains　challenging,　that　a　perfect　solution　has　yet　to　be　achieved.　Herein,　we　provide　a　comprehensive　and　in-depth　inspection　of　the　state-of-the-art　ISEs,　aiming　at　revealing　the　underlying　Na+　conduction　mechanisms　at　different　length　scales,　and　interpreting　their　compatibility　with　the　Na　metal　anode　from　multiple　aspects.　A　thorough　material　screening　will　include　nearly　all　ISEs　developed　to　date,　i.e.,　oxides,　chalcogenides,　halides,　antiperovskites,　and　borohydrides,　followed　by　an　overview　of　the　modification　strategies　for　enhancing　their　ionic　conductivity　and　interfacial　compatibility　with　Na　metal,　including　synthesis,　doping　and　interfacial　engineering.　By　discussing　the　remaining　challenges　in　ISE　research,　we　propose　rational　and　strategic　perspectives　that　can　serve　as　guidelines　for　future　development　of　desirable　ISEs　and　practical　implementation　of　high-performance　SMBs.