To retain the two-layer stratified corium melt pool inside the RPV under severe accident, the In-Vessel Retention (IVR) strategy provides sufficient outside flood cooling. The key to ensure the effectiveness of IVR strategy is to measure whether the cooling ability is sufficient to cope with the heat flux density on the RPV wall. The heat flux density in the metal melt pool is higher than that in the oxide melt pool and may exceed the local critical heat flux. Due to high degree of uncertainty, it is difficult to estimate heat flux density. It is essential to study the heat transfer characteristics of the metal melt pool. To further study the heat transfer characteristics of the metal melt pool, the experimental setup with rectangular melt pool cavity was designed based on the geometry and size of the Chinese advanced pressurized water reactor. The metal tin with Pr number of 6 × 10–3 was applied as simulant, which is on the same order of magnitude as the molten metal in the real corium pool. With the bottom heating device and cooling water channels adjacent to the side wall, the experiment setup can work under the boundary conditions and heating mode which are similar with the real corium pool. A series of experiments will be conducted to investigate the effects of cooling conditions, heating power, simulating media height. The experimental results will help to understand the heat transfer mechanism of the metal layer melt pool and predict the boundary heat flux density.