The　paper　takes　the　small-sized　ordinary　greenhouse　and　the　PCM　greenhouse　we　built　as　the　research　object.　Contrastive　experiments　were　done　on　the　project.　Through　measuring　and　comparing　the　temperature　changing　of　the　indoor　air,　the　outer　and　inner　surfaces　of　the　north,　east　and　west　wall,　it　discusses　the　effects　of　the　PCM　wallboard　on　the　indoor　thermal　environment,　analyzes　the　feasible　approaches　of　reducing　the　heating　energy　consumption　in　winter,　and　preliminarily　estimates　the　effects　of　the　PCM　wallboard　on　aspect　of　the　energy　saving　for　the　greenhouse.　The　experimental　results　show　that　applying　appropriate　PCM　to　the　inner　surface　of　the　north　wall　in　the　greenhouse　can　increase　the　indoor　air　temperature　dramatically　as　well　as　reduce　power　consumption　significantly,　and　make　the　power　saving　rate　eta　reach　8%　as　a　result.