Ground　source　heat　pump　(GSHP)　use　the　ground　as　both　a　sink　and　a　source　for　thermal　energy　needed　to　heat　and　cool　buildings.　Thermal　energy　is　transferred　between　the　earth　and　the　GSHP　by　fluids　that　circulate　in　＂underground　energy　collector＂　which　are　made　of　polyethylene　or　steel　pipes.　We　can　take　use　of　superficial　geothermal　energy　more　efficiently　if　we　acknowledge　the　condition　of　underground　temperature　field.　And　we　can　lay　the　underground　energy　collector　rationally　to　improve　the　efficiency　of　heat　exchanging　and　decrease　the　inputting　cost.　The　author　built　a　test-bed　to　study　the　diversification　of　underground　temperature　field　when　the　GSHP　operate.　We　try　to　find　out　decent　number　of　energy　wells　and　optimal　depth　so　as　to　increase　the　ratio　of　costing　and　producing.　We　believe　the　experiments　are　valuable　to　GSHP　projects.