Abstract: The ratio of bubble departure diameter in pool boiling and flow boiling was introduced to modify the suppression factor S in the present study, then the modified S was used to substitute the suppression factor which appears in Lee-Mudawwar subcooled boiling CHF model. In addition, the bubble behavior in vertical rectangular channel was also analyzed. Then a new subcooled boiling heat transfer model was established based on the foregoing study. And the main factors which influence the heat transfer coefficient were also analyzed. Furthermore, the dependability of the model was validated through the comparison between the experimental and calculated values. The results show that the present model can be used to predict the subcooled boiling heat transfer characteristic in vertical narrow rectangular channel.