Abstract: In this work, the DEBORA subcooled boiling flow experiments were employed as benchmark and simulated by Fluent. The uncertainty from boundary conditions and its influence trend of the prediction of subcooled boiling flow were analyzed by using deterministic sampling method. The distributions of radial parameters were calculated and the confidence intervals were obtained. Besides, the uncertainty source contributions on radial parameters were also analyzed. The results show that the uncertainties of the inlet temperature and the wall heat flux play predominant roles on the prediction of radial void fraction, while the uncertainties of the operating pressure and the inlet temperature dominate calculation of radial liquid temperature.