This　paper　established　a　3D　heat　transfer　model　to　simulate　the　running　state　of　the　vertical　U-tube　ground　heat　exchanger　(GHE),　which　introduced　the　heat　exchange　function　as　the　boundary　condition　for　the　inlet　of　the　U-tube.　The　author　proposed　a　new　method　to　calculate　the　distance　between　individual　line　heat　source　and　the　district　center,　and　derived　the　solution　by　finite　volume　method.　The　model　can　meet　the　requirement　for　the　engineering　precision　by　comparison　between　numerical　and　experimental　results.　Furthermore　it　presented　the　temperature　distribution　of　the　fluid　inside　the　U-tube,　and　also　analyzed　the　effects　of　the　depth　of　borehole　on　thermal　interference　between　the　U-tube　two　legs.