The　performance　of　heat　pump　ventilation　heat　recovery　system　can　be　effectively　improved　using　multiple-loop　independent　compression　cycle.　The　influence　of　the　DR　change　on　the　performance　of　dual-loop　system　was　predicted　through　calculation　to　explore　the　influence　of　the　change　in　displacement　ratio　(DR)　on　the　performance　of　the　system　and　the　direction　of　further　improving　the　performance　of　the　system.　The　optimum　DR　in　dual-loop　system　was　calculated.　The　performance　differences　of　two　dual-loop　heat　pump　systems　with　different　DR　values　were　compared　by　experiments.　Results　show　that　the　optimum　DR　is　between　0.8040　and　0.9206,　and　this　optimum　DR　maximizes　the　COP　of　the　system.　Experimental　results　show　that,　compared　with　the　COP　of　the　system　with　the　DR　of　2,　that　of　the　system　with　the　DR　of　0.5　can　be　increased　by　14.8%.　Compared　with　the　overall　COP　of　the　triplex　loop　system　with　the　same　displacement　in　each　loop,　that　of　the　system　with　the　DR　of　0.5　is　even　higher　under　certain　test　conditions.　The　comparison　results　of　COP　changes　are　in　accordance　with　the　prediction　of　simulation　calculation.　Therefore,　a　reasonable　increase　in　the　displacement　of　the　low-pressure　loop　in　the　multi-loop　heat　recovery　heat　pump　system　will　improve　the　system　performance.　(c)　2020　Elsevier　B.V.　All　rights　reserved.