A　plate　heat　pipe　heat　exchanger　for　room　ventilation　is　designed.　Its　performance　affected　by　vacuum　is　experimentally　investigated.　Experiments　were　carried　out　under　the　simulated　summer　condition.　The　air　volume　rates　were　changed　at　60,　90,　120,　and　150　m3/h.　The　fresh　air　temperature　varied　from　27　to　40°C,　whereas　the　return　air　temperature　was　kept　at　about　24°C.　Results　show　that　the　conservation　effect　of　the　heat　pipe　heat　exchanger　is　prominent　and　the　maximum　effectiveness　is　about　60%.　The　change　for　effectiveness　is　slightly　different　from　variation　of　vacuum.