Bubble behavior was simulated to analyze the mechanism of subcooled boiling in a micro-channel. Bubble growth, condensation, and collapse in subcooled boiling, as well as the function of the degree of subcooling, lift-off diameter, heat flux, and mass flux are discussed. The influence of surface tension on interfacial heat transfer is likewise presented. In the calculated results, both onset of nucleate boiling and boiling heat transfer are influenced by micro-channel size. The simulated flow pattern corresponds with some experimental results. Findings on the boiling heat transfer from the simulation were compared with experiments.