Abstract: The paper starts with a study of the effect on the internal flow field and separation performance of a heavy medium cyclone produced by different types of feed inlet structures, and then a new type of feed inlet structure is proposed, and both its advantages and disadvantages are studied and analyzed. Two different types of feed inlet structures and their respective features are compared in terms of the internal pressure distribution. Velocity distribution and density distribution, by using the 3-dimensional simulation analysis software. As evidenced by study result, compared with the other types of feed inlet structures, the spiral type offers the special features of being able to ensure a more stable internal flow field and a higher separation precision. Its other attractions include less energy consumption, higher efficiency and longer service life. The study result provides a theoretical and and technical support for the application of structurally novel H. M. cyclone in the coal washing sphere.