Flow boiling heat transfer and pressure drop of water in a minichannel has been experimentally studied to investigate the effect of pressure. The results of experiments were compared with selected existing correlations. The experimental apparatus consists mainly of gear pump, flowmeter, pre-heater, pressurizer, condenser, and evaporator for control of water quality at the inlet of test section. The test section is a round minichannel of 1.73 mm inside diameter, made of 316 stainless steel. And the test section tube is heated by a direct DC current through the tube. The ranges of the major experimental parameters in this study are 100 kg/m2s of mass flux, 30～70 kW/m2 of heat flux and 0.0～0.3 of inlet vapor quality. The experimental result showed that the flow boiling heat transfer coefficients in a minichannel are in the range of 3～25 kW/m2K and they were affected by pressure and local mass quality while independent of heat flux. Flow boiling pressure drop was also affected by pressure.