Abstract: In order to regulate and control the dense medium cyclone separation effects for separation density of the second segment, the paper added a magnetic structure to the coils located in the conical part of cyclone, under the electromagnetic field, by changing the intensity of magnetic field, the medium distribution test and -3mm coal slime separation test had been done. The test results show that when the inner magnetic structure was added to the upper part of coils located in the conical part of cyclone, compared with using coils only, under certain condition of intensity of magnetic field, lower ash of clean coal and high ash of coal tailing indicated the improvement of the separation efficiency. The magnetic system was analyzed by the finite element software ANSYS, the results showed that the additional magnetic structure can change the direction of the magnetic field, increase the concentration of the magnetic field energy and improve the magnetic force, so as to improve the separation effect.