This　paper　focuses　on　the　effect　of　supply　temperature,　water　flow　velocity,　and　tube　spacing　on　the　hot　water　floor　heat　exchanger　through　experiments.　The　testing　experiments　were　carried　out　in　four　rooms　with　the　same　two-pass　style　arrangement　and　different　tube　spacings　in　an　office　building　in　Beijing.　Heat　flowand　floor　surface　temperature　were　analyzed　and　compared　as　the　supply　water　temperature　and　water　flow　velocity　were　varied　independently,　and　non-uniformity　of　floor　surface　temperature　in　different　tube　spacings　was　determined.　The　optimal　ranges　of　supply　water　temperature,　water　flow　velocity,　and　tube　spacing　for　Beijing＇s　office　buildings　were　presented.