Abstract: Rare earth elements exhibit outstanding physical and chemical properties, presenting distinguished performance in optics, electronics, and magnetism, and play an irreplaceable role in cutting-edge technology fields such as defense, optical fiber communication and aerospace. To date, the leaching efficiency of rare earth ore is far away from optimal level. Therefore, it is necessary to exert the utmost effort to improve leaching efficiency and examine internal reaction mechanisms. In fact, it is difficult to investigate internal reaction mechanisms and comprehensively measure the leaching process in experiments. In this work, a two-dimensional mechanistic simulation model based on computational fluid mechanics incorporating the shrinking unreacted core model for ion-type rare earth ore leaching was developed and validated with experimental data. It investigated the evolution of chemical components over time and examined the effects of porosity and the initial velocity of the leaching agent on the leaching process. The results showed that the volume fraction of the rare earth ore decreased from an initial 65% to 58.4% after 600 min of leaching. Contrary to the expectation, the leaching rate decreased with increasing porosity of the rare earth ore. Additionally, it was found that a higher leaching rate could be achieved with a higher inlet flow velocity of the leaching agent, but the extent of the increase slowed down. In the pursuit of a greater rare earth leaching rate, while effectively controlling production costs, it is recommended that the inlet velocity be maintained between 0.004 m/s and 0.006 m/s.