The　energy　consumption　characteristics　of　the　heat　pump　system　were　analyzed,　in　which　the　Supply　-　Discharge　bathing　water　was　used　as　circulation　water.　The　entropy　flow　S-f　and　entropy　generation　S-g　about　heat　pump　system　in　irreversible　cycle　are　separately　discussed　in　winter　and　summer.　Compare　entropy　flow　and　entropy　generation　of　energy　saving　system　with　ordinary　air-conditioning　system.　The　influence　of　circulation　water　temperature　on　unit　entropy　increasing　is　researched　qualitatively.　The　results　analyzed　of　entropy　increasing　shows　that　the　sewage　source　heat　pump　has　good　effect　on　energy　saving　and　unit　performance　improving.