Heat　transfer　characteristics　of　supercritical　water　in　a　vertical　upflow　tube　with　full-circumferential　heating　are　investigated　experimentally.　The　effects　of　mass　flow,　heat　flux,　and　pressure　on　the　heat　transfer　are　analyzed　via　the　experimental　data　in　detail.　Because　of　the　abrupt　variation　of　the　thermophysical　properties　under　supercritical　pressure,　heat　transfer　enhancement　phenomenon　is　observed　when　the　fluid　bulk　temperature　approaches　the　pseudo-critical　temperature.　With　increasing　of　mass　flow　and　pressure,　and　with　decreasing　of　heat　flux,　heat　transfer　is　enhanced　obviously.　By　curve-fitting　of　the　experimental　data,　an　empirical　correlation　for　forced　convection　heat　transfer　of　supercritical　water　is　obtained　with　average　relative　error　of　11.8%.