Ventilation　heat　recovery　is　an　important　way　to　effectively　reducing　energy　consumption　of　buildings.　To　improve　the　system　performance　of　a　heat　pump　heat　recovery　system　under　large　temperature　difference　conditions　in　winter,　a　triplex　loop　heat　pump　system　was　proposed　to　replace　single　loop　heat　pump　system　under　the　same　working　conditions.　A　prototype,　which　contained　three　independent　heat　pump　cycles　was　made.　In　the　case　where　the　indoor　temperature　was　constant　at　20　℃　and　outdoor　temperature　dropped　from　15　℃　to　-20　℃,　the　fresh　air　treatment　process,　the　system　pressure　ratio,　the　circulation　mass　flow　rate,　the　heating　capacity　and　the　system　COP　of　the　heat　recovery　system　were　fully　tested　and　analyzed.　Results　show　that　the　mass　flow　rate　and　the　pressure　ratio　of　the　triplex　loop　heat　recovery　system　decrease　with　the　decrease　of　outdoor　temperature　but　still　higher　than　that　of　the　traditional　system,　and　the　heating　capacity　and　COP　increase　with　the　decrease　of　outdoor　temperature.　Under　the　experimental　conditions,　the　COP　of　the　triplex　loop　system　has　an　advantage　over　the　traditional　heat　pump　system.　When　the　outdoor　temperature　is　-20　℃,　the　heating　capacity　increases　by　12.43%,　and　the　COP　of　the　system　increases　by　23.1%.　The　performance　of　the　triplex　loop　heat　pump　heat　recovery　system　is　good　in　winter.　In　most　cases,　the　system　performance　is　better　than　that　of　the　traditional　single　loop　heat　pump　heat　recovery　system.　©　2019,　Editorial　Department　of　Journal　of　Beijing　University　of　Technology.　All　right　reserved.