Cable　accessories　are　critical　components　of　cable　lines,　with　their　interface　structure　serving　as　a　primary　weak　point　in　operational　performance.　Accurately　measuring　and　assessing　interfacial　performance　is　paramount.　Due　to　their　destructive　nature,　existing　insulating　performance　testing　methods　fail　to　assess　the　quality　of　cable　accessory　installations　on-site　effectively.　This　study　presents　a　non-destructive　airtightness　testing　method　for　assessing　the　interfacial　performance　of　cable　accessories.　Based　on　the　gas　leakage　characteristics,　two　airtightness　indicators,　namely　leakage　coefficient　and　withstand　pressure,　are　defined　and　calculated　to　assess　the　sealing　performance　of　the　interface　structure.　Moreover,　the　proposed　method　is　applied　to　interfaces　with　varying　interfacial　pressures　and　roughness　levels,　and　compared　with　results　obtained　from　existing　insulating　performance-focused　evaluation　systems.　The　comparative　analysis　reveals　a　strong　correlation　between　airtightness　and　insulating　performance　indicators,　confirming　the　feasibility　and　validity　of　the　airtightness　testing　method.　With　its　comprehensive　advantages,　the　proposed　method　can　be　utilized　for　on-site　quality　assessment　of　installed　cable　accessories,　providing　a　novel　technological　approach　to　enhance　the　operational　capabilities　of　cable　systems.　©　1986-2012　IEEE.