Abstract: Using CFD (Computational Fluid Dynamics) code, numerical investigations on heat transfer behavior of supercritical water were conducted. The IAEA (International Atomic Energy Agency) computational benchmark about heat transfer behavior of supercritical water in vertical pipe was finished. The results are in accord with experimental values. The SST (Shear-Stress-Transport) model is able to reproduce the heat transfer behavior of supercritical water, but it is sensitive to the grid, and needs suitable grid to match. The suitable grid possibly relates to the state of supercritical water. These conclusions are able to guide the numerical simulation on heat transfer behavior of supercritical water.