This　study　experimentally　investigated　SiC-water　nanofluids　flow　and　heat　transfer　characteristics　in　three　types　of　structure　multiport　rectangular　minichannel　flat　tube,　including　smooth　tube　and　micro-fin　tube　with　two　different　spacing　of　fins.　The　volume　concentrations　of　nanofluids　is　0.005%,　0.01%　and　0.1%.　The　range　of　Reynolds　number　is　150-5300.　The　experimental　results　indicate　that　the　micro-fin　structure　has　no　effect　on　the　flow　characteristic　of　nanofluids.　However,　the　spacing　of　micro-fin　has　some　effect　on　the　heat　transfer　characteristic　of　nanofluids.　The　increase　ratio　of　nanofluids　heat　transfer　in　micro-fin　tube　is　lower　than　that　of　smooth　tube,　which　attributes　to　the　presence　of　micro-fin.　Finally,　it　is　shown　that　the　maximum　PEC　of　0.01%　nanofluids　is　1.68　at　Re　≈5100　in　smooth　tube.　©　2018,　Science　Press.　All　right　reserved.