For the design and safety studies of steam generator in the China LEAd-based Reactor (CLEAR) project, it is necessary to investigate the consequences of a Steam Generator Tube Rupture (SGTR) accident which could result in a reaction between Lead-Bismuth Eutectic (LBE) and highly pressurised water. Some experiments have been conducted to investigate the thermal-hydraulic behaviour of the molten LBE/water interface; the whole fragmentation processes of these experiments were visually observed with a high-speed video camera, and the transient pressure histories were measured by high-frequency piezoelectric pressure sensors. The effects of LBE temperature, water temperature, nozzle diameter and injection velocity were investigated. Visualisation films indicated that the explosion phenomenon happened readily at lower water temperature. The peak pressure decreased with increasing water temperature, nozzle diameter and injection velocity. However, the peak pressure first increased and then decreased as the LBE temperature increased. The shape of the debris became round at higher water temperature, and a needle-like shape was observed at lower temperatures. Debris analysis results showed that the debris sizes of 2.8–6.7 mm had the largest mass fraction. By comparison with the theoretical calculation, it was found that the fragment diameters measured in the present study agreed well with Weber number theory. Thus, it was demonstrated that the fragmentation mechanism was controlled by shearing stress under the present experimental conditions.