Abstract: Based on the near wall bubble crowding mode,aimed at the two-phase flow boiling heat transfer at high pressure and low flow rate conditions,a critical heat flux prediction model for low vapor quality region was developed in this paper.The limiting transverse mass flux crossing the interface of the bubbly layer and core was determined from a momentum balance in the model.A formula for detached bubble diameter considering buoyancy and some existing correlations for bubble detachment point,turbulent velocity profile and void fraction were applied in the model,and the critical void fraction of wall bubbly layer were presented based on the experimental data.A good agreement is achieved between the results and experimental data,which implies that the CHF model is accurate at high pressure and low flow rate.