Abstract: In order to accurately predict the critical heat flux（CHF） in pressurized water reactor core fuel assembly, the effects of spacer grids, cold walls and non-uniform heat flux in rod bundles on CHF are analyzed. Simultaneously, six CHF mechanism models based on different physical hypothesis are comparatively researched, and the development methods for CHF correlations are put forward. Advantages and disadvantages of CHF mechanism models and empirical correlations in the prediction of bundle CHF are obtained. It is suggested that the expanding of existing CHF experimental database, the optimizing of development methods of CHF correlations, and the developing of rod bundle CHF mechanism models shall be carried out.