The　aim　of　this　paper　is　to　establish　the　heat　transfer　model　of　all-glass　vacuum　tube　collector　used　in　forced-circulation　solar　water　heating　system.　In　this　model,　the　simplified　heat　transfer　of　collector　is　composed　of　the　natural　convection　in　single　glass　tube　and　forced　flow　in　manifold　header.　Thus　the　heat　balance　equation　of　water　in　single　tube　and　the　heat　balance　equation　of　water　in　manifold　header　have　been　established.　The　flow　equation　is　also　built　by　analyzing　the　friction　and　buoyancy　in　tube.　Through　solved　these　equations　the　relationship　between　the　collector　average　temperature,　the　outlet　temperature　and　natural　convection　flow　rate　have　been　obtained.　From　this　relationship　and　energy　balance　equation　of　collector,　the　collector　outlet　temperature　can　be　calculated.　The　validated　experiments　of　this　model　were　carried　out　in　winter　of　Beijing.　(C)　2010　Elsevier　Ltd.　All　rights　reserved.