A method to predict the probabilistic distribution of channel coolant flow rate was developed for a boiling-water-cooled, pressure-tube-type reactor. This method deals with the probabilistic deviation of core flow distribution and total coolant flow rate based on the characteristics of the correlation between two-phase pressure drop of a primary core cooling system and the characteristics of the recirculation pump Q-H. The effect of local and global uncertainties on the probabilistic variation of channel coolant flow rate is discussed in terms of coolant flow correlation among all of the pressure tube channels. The probabilistic deviation of channel coolant flow rate due to uncertainties in fabrication tolerances, experimental data, and physical properties has been evaluated for various operating conditions of the FUGEN reactor. Predicted channel flow deviations were in good agreement with the deviation of actual measured data in the FUGEN reactor.