Based　on　the　design　method　of　heat　exchanger　and　fin　theory,　a　model　of　radiant　heat　exchanger　is　established　and　used　to　analyze　the　heat　transfer　characteristics　of　a　radiant　floor　cooling　system.　The　calculations　of　simulation　are　compared　with　the　experimental　data　under　cooling　condition.　It　is　proved　that　the　model　can　be　used　to　analyze　heat　transfer　characteristics　of　the　floor　heat　exchanger　and　to　supply　its　design　method　of　the　radiant　floor　cooling　system.　When　the　supply　temperature　maintains　16-18°C,　flow　velocity　is　about　0.25-0.5　m/s,　and　the　spacing　shifts　form　150　mm　to　200　mm,　the　heat　flux　of　the　radiant　floor　heat　exchanger　can　achieve　32-40　W/m2,　in　the　meantime,　the　floor　temperature　will　be　above　20°C　without　the　danger　of　condensation　basically.