Abstract: China′s northwestern and northeastern regions are rich in coal resources. However, the local coal-related enterprises are facing not only technological challenges but also those imposed by extreme environment. Yet, few cases in this respect have been reported in points of detail. The control system developed for Mongolia′s ETT Coal Preparation Plant proves to be a solution to the problems. To ensure steady operation of the control system, the system 800xA DCS of the ABB company is introduced, and multiple technical measures, such as fitting radiators and dustproof and waterproof enclosures, are adopted for protection against the impact of extreme environment. In regard to network structure, the plant is provided with CS redundant server and AS server for ensuring the system′s stable communication and operation. The system is able to work in either centralized or local control mode which can be flexibly changed over depending on operating conditions. For ensuring safety of operators and equipment, the system is provided with audio and visual alarm devices and the means for guarding against accidental start-up. With the use of the system, coordinated control of level, density and slime content of medium suspension as well as blending of coal, thickening and dosing of agents and press filtration operation can all be made automatically in an intelligent manner. Application of the control system at ETT Plant has made it possible to carry out real-time collection and display of key operating parameters, optimize coal washing process and cut equipment shutdown time. Furthermore, its use has led to a save of the time required for making remote control and resetting after clearance of faults by 15 ~ 30 minutes per day, cut of the shutdown time of equipment for maintenance by 10 ~ 12 hours each month, and cut of labor cost due to reduction of two operators. The DCS control system proves to be reliable in operation in ETT Plant and its use has successfully coped with the challenge posed by extremely harsh environmental conditions, guaranteed uninterrupted coal washing operation and quality consistency of coal products. The successful use of the control system can serve as a valuable reference for development of intelligent coal preparation plants in China′s northwestern and northeastern regions.