Abstract: As the main equipment selected by coal separation plant, for dense-medium cyclone, its inner-wall abrasion directly influences its separation efficiency and continuity of production. In the paper, to solve the problem that conventional detection methods cannot efficiently check out real-time flaws in heavy medium cyclone inwall which is worn by ore pulp, the working process and imaging principle of ultrasonic phased array technology were described in detail. Furthermore, through the experimental study on heavy medium cyclone model, it demonstrated that the color palette on the detection device used different colors to represent strength of reflected signals, i.e. different colors were used to represent sound pressures in all scanning regions and the components of internal defects reflected by sound pressures were real-time display. So it is concluded that ultrasonic phased array technology can present wearing flaws in heavy medium cyclone inwall by real-time imaging and the error of test items is less than 8%.