A　quasi　two-stage　compression　heat　pump　system　coupled　with　ejector　was　designed,　in　which　the　ejector　replaces　the　throttling　element　in　conventional　heat　pump　with　economizer.　When　the　condensation　temperature　kept　at　45C　and　the　evaporating　temperature　varies　from　-8C　to　-25C,　the　performances　of　the　heat　pump　prototypes　were　tested　in　detail.　The　experimental　results　demonstrate　that　the　heat　pump　system　coupled　with　ejector　owns　better　performances　than　the　quasi　two-stage　heat　pump　system　when　it　running　under　the　designing　conditions,　but　its　performances　will　decrease　under　the　off-designing　conditions.　The　coupled　heat　pump　system　with　the　ejector　by　optimum　design　can　obtain　excellent　performances　in　a　wide　range　of　operating　conditions,　and　its　heating　COP　can　be　about　10%　higher　than　the　heat　pump　system　without　the　ejector.