Abstract: In order to solve the problem of lower thermal conductivity and heat transfer performance, the single-phase flow and heat transfer characteristics of nanofluids with different volume fraction ( ranging from 0. 001% to 0. 1%) inside the multiport mini-channel flat tube ( MMFT) was investigated. Water-based SiC nanofluids was used as the working fluid. The hydraulic diameter of the flat tube’ s rectangular channel was 2. 08 mm and the Reynolds number varied from 150 to 5 200 approximately. The experimental results indicate that the Nusselt number increases at the beginning and drops later with the increase of volume concentration. When the Reynolds number reaches to 5 200, the largest growth rate of Nusselt number runs up to 80. 8% at a volume fraction of 0. 01% compared with the results of base fluid. Results also show that there are smaller increase in resistance , along with the enhancement of heat transfer effect.