<p>Reactive force field parameters are re-optimized for simulating the stress corrosion cracking (SCC) of iron-based material in a supercritical water environment. The parameters for molecular dynamics (MD) simulation are determined by fitting the adsorption energies of H, OH, and H₂O on an Fe(110) surface obtained by reactive force field to the density functional theory (DFT) calculations. The errors of adsorption energies for the most stable positions are less than 5%, and our parameters are in good agreement with the DFT calculations. The development of Fe/O/H parameters is expected to contribute to SCC simulation of iron-based materials in supercritical water environments.</p>