Abstract: In accordance with the leaching mechanism, the pH value was maintained within the range of 3.5~5, which could minimize rare-earth waste.The pH mathematical model of leaching and impurity removal process was established using mathematical methods. Then, overall scheme of the system was designed using characteristic analysis of the model. To realize the control of process pH value, the system was controlled employing fuzzy control in combination with the incremental digital PID by performing the matlab simulation experiment of the parameters self-turning fuzzy PID.The simulation results show that the system has smaller steady-state error and shorter response time than the general control mode. Thus the validity and advancement of the control strategy were verified.