In order to overcome the harsh decomposition of chromite ore by sulfuric acid, both mechanical activation and oxidant were used as a new method to intensify the decomposition process by sulfuric acid. The effects of ratio of liquid to solid, concentration of H2SO4, mechanical activation, oxidant addition and leaching temperature on the leaching rate of Cr from chromite ore originated in South Africa were examined, and the leaching kinetics of Cr was analyzed. The results showed that the optimum leaching conditions were the ratio of sulfuric acid to solid 2.4 mL/g, H2SO4 concentration 80%(w), mechanical activation time 20 min, oxidant addition 13%(w), leaching temperature 120℃ and leaching time 5 h. Under the optimum conditions, the leaching rate of Cr reached 92.36%. The leaching process of Cr was in line with the unreacted shrinking core model.