Abstract: To overcome the difficulty in making online control of separation effect of the 2nd-stage of the 3-product H. M. cyclone, the concept of introducing an additional medium supply system and an inner circulation system for the cyclone′s 2nd-stage is proposed with an aim to form a small medium supply system capable of making inner circulation for this stage. In addition, the 3-product H. M. cyclone with its 2nd-stage provided with a double medium feeding system as well as the corresponding cycloning process are developed. The use of the technology proves to be capable of attaining the goal of making online improvement of the separation effect of the 2nd-stage of the cyclone, eliminating the need for the change of the cyclone′s underflow orifice—the last technological resort currently applied by domestic coal preparation plants for making such improvement. The technology provides a new thought for realizing precision separation in the 2nd-stage of a 3-prooduct H. M. cyclone.