CaCl 2 can be sprayed onto sinter surface, which can improve the low temperature reduction degradation index (RDI +3.15 ) of sinter. This has been recognized; however, there are various opinions on the inhibition mechanism of it. At the same time, the corrosion of Cl element on equipment is very serious. First-principle calculations based on density functional theory were performed to investigate the binding mechanisms of calcium species on a α-Fe 2 O 3 (0 0 1) surface. This is crucial in demonstrating the role of the CaCl 2 on improving the low temperature reduction degradation index. It has been determined that Cl could greatly increase the adsorption of the vacuum layer for the Ca/Fe 2 O 3 system and the relaxation produced by adsorption made bond length decrease, bond energies increase and structure compact. Those are the main reasons that inhibiting the reduction disintegration of sinter.