Based　on　the　statistical　work　on　outdoor　average　wind　speeds　in　winter　or　summer　and　hourly　rainfall　condition　of　representative　cities　in　different　climate　zones,　the　method　to　combine　theoretical　research　and　data　statistics　is　adopted.　Firstly　the　theoretical　calculation　methods　of　convection,　radiation　and　vaporizing　heat　transfer　coefficients　at　exterior　building　surface　are　analyzed　respectively,　and　then　the　total　heat　transfer　coefficient　is　calculated.　It　shows　that　the　wind　speed　of　extreme　hot-humid　climate　zone　is　much　higher　than　that　of　inland　areas　and　the　surface　moisture　probability　of　extreme　hot-humid　climate　zone　is　up　to　0.042.　The　total　heat　transfer　coefficient　for　the　cities　located　in　northern　area　or　southern　area　with　climatic　features　of　very　low　wind　speed　and　relatively　small　surface　moisture　probability,　can　be　in　accordance　with　design　code,　ignoring　vaporizing　heat　transfer.　However,　vaporizing　heat　transfer　must　not　be　ignored　for　cities　with　high　wind　speed　and　great　rainfall　or　relatively　low　wind　speed　and　especially　frequent　rainfall　in　southern　area.　Finally,　this　paper　takes　building　in　extreme　hot-humid　climate　zone　as　research　object　to　calculate　the　total　heat　transfer　coefficient　at　moisture　and　exterior　building　surface　in　summer,　it　turns　out　that　the　calculated　value　is　up　to　39.0　W/(m2•K)　and　much　higher　than　recommended　value.　©　2019,　Editorial　Board　of　Acta　Energiae　Solaris　Sinica.　All　right　reserved.