Mill rejects are a kind of solid wastes in coal-fired power plants, which can cause a lot of air pollution problems. At present, there are several treatments for mill rejects, but they all have some shortcomings. A positive pneumatic conveying system general used for powder was successfully applied to mill rejects with special conveyor, valves and running process, which could make a great breakthrough on the technology and application. With advantages of simple, flexible layout, small occupation of land, no water wasting, and low power consumption due to the conveying air coming from the air compressor station in power plant, this technology is worthy of popularization.