In this paper, two-phase boiling heat transfer characteristics and heat transfer coefficient of HFE-7100 in vertical mini-channels have been investigated. The mini-channel consists of 22 parallel square channels. The channel has 4 mm × 0.5 mm cross-section and is 120 mm long with hydraulic diameter of 889 μm. The temperature of channel wall was measured at 9 locations along the vertical direction. The experiments have been conducted under various operating conditions such as different heat flux and mass flux. The heat flux was varied in the range of 50 to 300 kW/m2 and mass flux were 68 and 114 kg/m2s. The test results indicate that depending on the dominant boiling heat transfer mechanism, the characteristics of boiling heat transfer coefficient varied. As a result of comparison predictions of the two-phase heat transfer coefficient using previous correlations with experimental values of the two-phase heat transfer coefficient, the correlation of Shah provides good predictions among 4 correlations.