The　heat　pump　system　with　flash-tank　could　effectively　improve　the　efficiency　and　reliability　of　air-source　heat　pump　(ASHP)　when　running　in　condition　of　low　ambient　temperature.　Based　on　scroll　compressor　with　flash-tank,　a　unit　suitable　for　cold　regions　is　designed.　The　whole　match　of　heat　pump　will　be　reached　by　adjusting　the　capillary　and　setting　down　a　control　project.　The　prototype　is　installed　in　Beijing　region　to　test,　and　then　it　shows　that,　it　could　run　reliably　for　a　long　time,　meanwhile,　its　heating　capacity　and　ratio　of　energy　and　efficiency　(EER)　are　improved,　so　it　could　meet　to　the　heat　need　in　winter　for　cold　regions.　In　conclusion,　ASHP　with　flash-tank　coupled　with　scroll　compressor　is　a　high-efficiency　and　clean　heating　way　suitable　for　cold　regions.