Abstract: A steady heat transfer experiment was carried out for predicting the critical heat flux （CHF） of convective boiling for a round sub-cooled water jet impingement on the jet stagnation zone of a hot surface. The effects of sub-cooling, jet velocity and jet diameter on the critical heat flux were fully investigated. An empirical correlation was proposed for predicating CHF using the preset experimental data. The study found that the CHF is a function of the sub-cooling, the jet velocity and the jet diameter. In especial, the sub-cooling has a significant effect on the CHF. Finally, a correlation was proposed for predicting CHF of convective boiling for sub-cooled water jet impinging on the jet stagnation zone, and the correlation agreed with the existing experimental data.