The　composite　phase　change　material　(PCM)　developed　by　our　research　group　was　analyzed　by　the　method　of　experimental　tests　based　on　our　previous　studies.　Applying　the　composite　PCM　to　the　inner　surface　of　the　north　wall　in　the　greenhouse,　building　the　ordinary　greenhouse　and　the　PCM　greenhouse　of　small　size,　the　comparative　experiment　was　conducted　on.　The　result　indicated　that　choosing　appropriate　PCM　to　the　inner　surface　of　the　north　wall　in　the　greenhouse　can　increase　the　indoor　air　temperature　and　the　inner　surface　temperature　of　walls　dramatically　as　well　as　reduce　the　power　consumption　significantly,　and　make　the　power　saving　rate　η　reach　8%　as　a　result.