Abstract: In order to improve the separation effect of a slime dense medium cyclone and enrich its control methods，taking magneticslime dense medium cyclone as a research object，considering the coil excitation mode of a now used magnetic cyclone，an additional magnetic structure made of low carbon steel material was designed to realize magnetic field targeted guidance and enhancement in the cyclone.The magnetic field simulation was analyzed by FEM analysis software ANSYS，and got the conclusion that the additional magnetic structure could change the magnetic field pattern in the separation area and enhance magnetic field intensity.The maximum magnetic field intensity in the center of the coil increased from 4 102 A/m without magnetic circuit to 4 930 A/m with a large magnetic concentrating ring，and the cohesive magnetic structure achieved 14 418 A/m because of its special structure design.Based on the simulation results，the magnetite powder distribution test and -3 mm coarse coal slime separation test under different magnetic field characteristics were tested and compared，and also obtained the magnetite and coarse coal slime distribution rule under different magnetic field intensity.The experimental results showed that，compared with the magnetic field without magnetic circuit，the external magnetic circuit structure would not change the distribution trend of underflow and overflow magnetite，and the coherent magnetic structure had a strong accumulation effect on magnetic field and increased the magnetic field intensity.For this reason，the overflow medium density decreased and underflow medium increased，the ash content of clean and tailing coal increased compared that without magnetic circuit，it got the conclusion that the cohesive magnetic structure could enhance the separation density of a slime dense medium cyclone.By adding a magnetic circuit to a cyclone，a new method and a new idea were provided for magnetic field design and separation effect control.It has a certain theoretical and practical significance for optimizing the magnetic field characteristics of a magnetic cyclone，and also，it’s of great value to fully explore the potential application of magnetic field in the separation process of slime dense medium cyclone，and enrich the separation theory of compound force field.