Abstract: Aiming at the prominent problems of equipment aging, insufficient control accuracy and others faced by the coal preparation plant during the capacity expansion and transformation process, a three-layer distributed architecture of "centralized management, decentralized control" is studied and adopted, S7-1516F-3PN/DP PLC, PROFIBUS-DP, and industrial Ethernet dual-protocol communication network are integrated to construct an automation control system. The system develops 327 functional blocks, including heavy medium density adjustment (FB) achieving a control accuracy of ± 0.003g/cm³, and flotation reagent control (FB) dynamically optimizing the ratio based on 128 fuzzy rules. After the implementation of the engineering, the E_p value of the heavy medium swirler is decreased from 0.045 kg/L to 0.03 kg/L, and the sorting accuracy is improved by 33.3%; The ash content of flotation clean coal is decreased by 1.77% to 8.86%; The interval time between equipment failures is extended by 70%, the nmuber of unplanned shutdown times is reduced by 62%, the system saves 278 000 kW·h of electricity quantity annually, decreases medium consumption by 1.2 kg/t of raw coal, achieves a comprehensive economic benefit of 12.6 million yuan, and the investment payback period is 2.3 years.