Abstract: Heavy medium separation is a highly effective coal washing method. Yet, its washing efficiency would be affected if its inner wall is damaged to a certain extent. Because of the difficulty in inspection and timely detection of the inner wall lining of the cyclone, a longer maintenance and replacement time is hence required, and the use of conventional detection method usually cannot meet with the expected results. To tackle this issue, an ultrasonic nondestructive detection platform is developed based on the ultrasonic phased array inspection technology. The platform is made up by phased array inspection system and image transmission system. Study made with the platform for detection of damages of cyclone′s inner lining in varying degrees at Wuobei Coal Preparation Plant shows that the conditions of the lining such as wear degree, no sign of wear and presence of wear-induced failure or defects can be directly discerned clearly in a timely and accurate manner; the time of shutdown of cyclone is reduced by 0.03 h for treating per 10 000 tons of raw coal due to reduced occurrence of accidents; as the adverse impact on cyclone′s separation sharpness caused by its structural wear is alleviated, a loss of 560 000 yuan can be avoid per year; and the use of the method can realistically lead to improvement of both management efficiency and economic performance of the Plant. The use of the technology is of great significance for the development of the technology for detection of damage of any closed-type equipment operating with complex cohesive medium, and it is likewise suitable for detection of wear conditions of different, kinds of similar equipment. The application of the technology proves to have a broad prospect.