Mechanical activation was used to strengthen the leaching of chromite ore in NaOH-NaNO3 binary molten salt.The effect of mechanical activation on the chromite particle size and distribution, surface area and lattice distortion was investigated.It was observed that mechanical activation changes the particle size and surface area, and the lattice distortion can also be found.The leaching rate of chromite ore after being mechanically activated was significantly enhanced.In addition, the particle size versus activation time and the leaching rate of mechanically activated chromite versus storage time in air were also studied.The results indicated that the particle size becomes smaller when prolonging the activation time in certain range, but not in the whole.The leaching rate of chromite ore when reacting immediately after being mechanically activated, is higher than that storing two days.