Abstract: Hydrocyclone is a continuous grading equipment and one of the most important equipment in the mineral processing industry. It uses centrifugal force to accelerate the settling speed of particles, usually forming a closed circuit grinding and grading process with a grinding machine. The grading effect has a very important impact on the efficiency of the grinding process. This paper analyzes the structure, working principle, and working characteristics of the hydrocyclone, and determines the key control parameters for the grading effect of the hydrocyclone. A set of cascade control strategy and automatic control system for the SABC grinding process of a certain beneficiation plant is designed and developed, which has been successfully applied in industrial sites to achieve stable control of the hydrocyclone and improve the stability of the overflow product of the hydrocyclone.