Air-supported　membrane　(ASM)　envelopes　offer　an　effective　solution　for　creating　large　interior　spaces　for　buildings　with　lower　energy　consumption　and　carbon　emissions.　However,　there　is　little　research　on　the　thermal　performance　of　ASM　envelopes,　particularly　regarding　the　natural　convection　within　the　air　interlayer　and　its　impact　on　thermal　resistance.　To　address　this　gap,　this　study　developed　a　numerical　model　of　ASM　envelopes　and　validated　it　through　experiments.　Subsequently,　a　numerical　investigation　was　conducted　to　analyze　natural　convection　and　thermal　resistance　while　considering　factors　such　as　indoor-outdoor　temperature　difference,　membrane　emissivity　and　air　interlayer　thickness.　Results　indicated　that　with　the　emissivity　increased　from　0.2　to　1,　the　thermal　resistance　of　the　air　interlayer　and　the　envelope　decreased　by　32.35　%　and　9.13　%,　respectively.　Besides,　the　thickness　of　air　interlayer　also　had　evident　effect　on　thermal　resistance.　When　it　increased　from　5　mm　to　35　mm,　the　thermal　resistance　of　the　air　interlayer　and　the　envelope　increased　by　156.19　%　and　14.74　%,　and　further　results　in　the　heat　transfer　decreased　by　13.85　%.　However,　the　convective　heat　transfer　would　remain　constant　when　the　thickness　exceeded　35　mm.　This　study　provided　valuable　reference　for　optimizing　the　design　of　ASM　envelopes　and　accurately　calculating　their　thermal　resistance.