Abstract: Aiming at the leaching process of NH₄Cl solution in EAF slag, the influence rule of the particle size and leaching temperature and time,as well as NH₄Cl concentration on leaching rate of Ca²⁺ are studied, and leaching kinetics model with self-resistance factor is established. Results show that the conversion rate of element calcium increases both with the increase of the leaching temperature and NH₄Cl concentration. The self-resistance factor for leaching process is in the range of 1.030 7 and 1.061 7 and the activation energy of leaching reactions is about 15.046 kj/mol which indicates that solid membrane diffusion limits EAF slag leaching process under the experimental condition.