Purpose:　The　purpose　of　this　paper　is　to　propose　a　grey　clustering　evaluation　model　based　on　analytic　hierarchy　process　(AHP)　and　interval　grey　number　(IGN)　to　solve　the　clustering　evaluation　problem　with　IGNs.　Design/methodology/approach:　First,　the　centre-point　triangular　whitenisation　weight　function　with　real　numbers　is　built,　and　then　by　using　interval　mean　function,　the　whitenisation　weight　function　is　extended　to　IGNs.　The　weights　of　evaluation　indexes　are　determined　by　AHP.　Finally,　this　model　is　used　to　evaluate　the　flight　safety　of　a　Chinese　airline.　The　results　indicate　that　the　model　is　effective　and　reasonable.　Findings:　When　IGN　meets　certain　conditions,　the　centre-point　triangular　whitenisation　weight　function　based　on　IGN　is　not　multiple-cross　and　it　is　normative.　It　provides　a　certain　standard　and　basis　for　obtaining　the　effective　evaluation　indexes　and　determining　the　scientific　evaluation　of　the　grey　class.　Originality/value:　The　traditional　grey　clustering　model　is　extended　to　the　field　of　IGN.　It　can　make　full　use　of　all　the　information　of　the　IGN,　so　the　result　of　the　evaluation　is　more　objective　and　reasonable,　which　provides　supports　for　solving　practical　problems.　©　2019,　Emerald　Publishing　Limited.