Flow boiling experiments were conducted in a staggered array micro pin fin channel heat sink with deionized water for two-phase pressure drop and boiling heat transfer at constant heat flux. Micro pin fin is a diameter of 400 mu m, height of 700 mu m and spacing of 300 mu m on copper heat sink. From the experimental results, at a vapor quality up to 0.043, the boiling heat transfer found to decrease as the vapor quality increased. The heat transfer coefficient is dependent on the mass flux and the pressure drop increased with the increase in mass flux.