Waste-gypsum of iron works was milled with CaO by planetary mill. TGA analysis of the ground material showed that the characteristics of pyrolysis after mechanical grinding was increased from 90% to 94% at 800℃. From the analysis of XRF the constituent of Na2O, SO3, Cl, PbO and ZnO were decreased while that of MgO, Al2O3, SiO2 and CaO increased a little. XRD analysis showed that high peak swere shown at PbO, PbCl2, PbO2 and Pb2O3 before mechanical treatment. After mechanical grinding of D-2, high peaks were shown at Pb3O4 and Pb5O8 showing the oxidation of Pb. These results showed that mechanochemical grinding in plnetarymill promoted to change chemical properties of waste gypsum of ironworks to oxydize the Pb component of waste gypsum of ironworks.