In　this　paper,　it　was　investigated　experimentally　that　the　effect　of　TiO2/R141b　nanofluids　as　working　fluid　on　the　thermal　performance　of　micro-channel　surface　at　different　pressures　and　particle　concentrations　of　nanofluids.　The　operational　pressures　in　this　study　were　0.86×105　Pa　and　1.0×105　Pa,　and　the　volume　concentration　of　nanoparticle　was　in　the　range　of　0.001%,　0.01%N　0.1%,　respectively.　In　operating　pressure　of　0.86×105　Pa,　nanofluids　with　concentrations　of　0.001%　and　0.01%,　the　corresponding　heat　transfer　coefficients　are　larger　than　that　of　the　base　fluid.　For　the　concentration　of　0.1%,　when　the　heat　flux　is　higher,　compared　with　the　pure　fluid,　the　heat　transfer　coefficient　is　lower.　At　pressure　of　1.0×105　Pa,　for　the　concentration　of　0.1%,　the　results　indicate　the　heat　transfer　deteriorated　in　the　range　of　higher　heat　flux.　Under　the　same　operating　pressure,　the　results　also　show　that　for　the　concentrations　of　0.001%　and　0.01%,　the　heat　transfer　enhancement　effect　is　not　obvious.　Heat　transfer　characteristic　for　TiO2　nanoparticle-coated　surface　with　rectangular　microchannels　were　experimentally　studied.　The　experimental　results　demonstrated　that　nanoparticle　deposed　covering　has　an　important　influence　on　the　heat　transfer　behavior.