The　convective　mass　transfer　coefficient　on　the　outer　surface　of　a　building　is　an　important　parameter　in　the　calculation　of　the　heat　and　moisture　coupling　of　the　enclosure　and　the　simulation　of　building　energy　consumption.　To　get　the　parameter　directly　and　accurately,　a　method　for　measuring　the　mass　transfer　coefficient　of　the　wall　on　the　building　surface　is　proposed.　The　mass　transfer　coefficient　of　the　naphthalene　specimen　can　be　calculated　by　measuring　the　mass　flux　and　surface　temperature　of　the　naphthalene　specimen.　To　verify　the　accuracy　and　reliability　of　the　method,　6　different　wind　speeds　were　set　up　in　the　wind　tunnel,　and　two　pieces　of　the　same　experimental　wall　were　made.　The　naphthalene　sublimation　method　was　applied　to　compare　with　the　traditional　thermal　balance　method.　The　results　show　that　the　surface　temperature　of　naphthalene　specimen　decreases　with　the　increase　of　wind　speed,　and　the　convective　mass　transfer　coefficient　increases　gradually.　The　results　of　the　two　methods　are　close　to　each　other.　The　difference　of　the　convective　mass　transfer　coefficients　between　the　two　methods　are　less　than　10%,　and　the　average　deviation　is　less　than　5%　under　different　wind　speed　conditions.　It　is　considered　that　the　method　is　feasible.　The　research　can　provide　guidance　for　testing　the　mass　transfer　coefficient　of　building　external　surface　under　outdoor　real　conditions,　and　is　also　significant　for　the　study　of　heat　and　moisture　coupling　calculation　and　the　evaporation　and　heat　transfer　of　walls.　©　All　Right　Reserved.