Ventilation　heat　recovery　is　an　important　means　of　effectively　reducing　the　energy　consumption　of　buildings.　The　improve　the　performance　of　a　heat　pump　heat　recovery　system　under　large　temperature　difference　conditions　winter,　a　triplex　loop　heat　pump　system,　which　contains　three　independent　heat　pump　cycles,　is　proposed　place　of　its　single　loop　counterpart.　Operating　characteristics　and　system　performance　were　analyzed　while　indoor　temperature　was　constant　at　20　degrees　C　and　as　outdoor　temperature　dropped　from　15　degrees　C　to　20　degrees　C.　Result　showed　that　with　the　decrease　of　the　outdoor　temperature,　the　mass　flow　rate　and　temperature　effectiveness　of　the　triplex　loop　heat　recovery　system　decreased　whereas　the　heating　capacity　and　the　coefficient　of　performanc　(COP)　increased.　Under　the　experimental　conditions,　the　COP　of　the　triplex　loop　system　had　an　advantage　ove　the　traditional　heat　pump　system　when　the　outdoor　temperature　was　below　2.5T.　When　the　outdoor　temperature　was　20　degrees　C,　the　COP　of　the　triplex　system　could　reach　9.33,　which　was　23.1%　higher　than　that　of　th　traditional　system.