This study aims to develop an experimental verification calculation model based on the open source CFD platform OpenFOAM to simulate boiling flow in single rod channel. Two-fluid model coupled with improved RPI wall boiling model (i.e. CHF model) was employed to investigate the departure from nuclear boiling (DNB) phenomena in a single rod under extremely high heat flux. The corrected wall heat flux partitioning model was implemented in the OpenFOAM to simulate two-phase boiling. A good agreement between the predicted CHF and experimental results was observed. On this basis, the effects of coolant mass flow and inlet subcooling on CHF were numerically studied. The results shown that two-fluid model coupled with CHF model was qualified to predict CHF accurately. This work can be referred when one predicts CHF in complicated geometry by CFD methodology.