The objective of this present research is to investigate the influence of bubble waiting time coefficient on subcooled flow boiling heat transfer in internal combustion engines and propose an approach to predict its value. The three-dimension simulated cooling jacket structure of valve bridges for forced water-cooling system was developed respectively. The numerical model for subcooled flow boiling based on two-fluid approach was established and calculated. Numerical results suggest that the bubble departure diameter increases with the increasing wall superheat or decreasing inlet subcooling. And the proportion of the quenching heat flux gradually rises and its peak value is delayed along the direction of the higher wall superheat when the subcooling degree decreases. The bubble waiting time coefficient has been found to have a significant impact upon the boiling heat transfer. A prediction model of bubble waiting time coefficient was presented with the verification of Abou-Ziyan's experimental results. The two-phase subcooled flow boiling model with considering bubble waiting time coefficient may be well applicable to boiling simulation on engine cooling jacket.