We studied the surface of stoichiometric α-Fe2O3 sample bombarded by Ar+ ion beam, the Fe++ ion was identified on it and the surface was found to become FeO-like in property. In addition, the results of UPS and XPS analysis indicated that OH-existed on the FeO-like surface during water adsorption and the Fe++ was the active center of water decomposition. We propose that water molecules adsorpted onto the surface can preliminarily be seperated into OH- and H+ due to the catalysis of 3d electrons of Fe++ ions on the surface. So, in order to raise the efficiency of photo-decomposition of water, it is not only important to modify the band structure, but also to create Fe++ ions on the α-Fe2O3 surface.