At　present,　the　application　of　R290　in　air　source　heat　pumps　is　still　in　the　stage　of　exploration　and　promotion.　In　previous　research　of　R290　heat　pump,　oil　blockage　of　throttle　component　frequently　occurred　in　heating　and　defrosting　process　and　the　failure　often　led　to　safety　problems　of　heat　pump.　In　this　paper,　the　measures　to　solve　the　problem　of　oil　blockage　are　studied　by　combining　the　physical　characteristics　of　R290　and　the　defrosting　dynamic　characteristics　of　R290　heat　pump.　Throttle　by-pass　method　(TBM),　suction　discharge　bypass　method　(SDBM)　throttle　discharge　throttling　method　(DTM)　are　proposed.　Meanwhile,　the　mechanism,　advantages　and　disadvantages　of　these　three　methods　are　discussed　when　mineral　oil　is　used　in　R290　heat　pump.　The　experimental　results　show　that　all　of　the　three　methods　can　effectively　eliminate　the　oil　blockage　of　R290　heat　pump　in　heating　and　defrosting　process　at　low　temperature　condition,　of　which　DTM　is　the　most　feasible　method　by　considering　reliability,　energy　efficiency　and　cost.　©　2020　International　Institute　of　Refrigeration.　All　rights　reserved.