Abstract: With the enhancement of automation management level and treating capacities of large coal preparation plants, a much higher demand is placed on the construction of reliable control systems, network structure and communication methods, and this promotes as a result the application of the DCS distributed control system in such plants.The DCS system is applied in place of the originally PLC programmable logic controller at Chahasu Coal Preparation Plant, Inner Mongolia.Following an elaboration on the difference between the two control systems, the paper presents a detailed description of the renovation project, system structure and both hardware and software configurations.Comparative analysis made in terms of reliability, cost effectiveness and expandability indicates that the DCS system is not inferior to the PLC programmable logic controller in performance and can meet the requirement of coal preparation plants.