The process parameters of variable diameter magnetic separation column have important influence on the separation of magnetic minerals.Based on the optimization of the structural parameters of the variable diameter magnetic separation column in the early stage, this experiment explores the influence of different operating parameters of the equipment on the magnetic mineral separation index.Under the same ore feeding conditions, orthogonal test and single factor test are used to optimize the working parameters such as the speed, current intensity, excitation period and separation time of the rising water flow of the variable diameter magnetic separation column.Taking the coarse concentrate of Anshan Dagushan Iron Mine Concentrator as the separation raw material, under the conditions of respective optimal operating parameters, the separation test results of the variable diameter magnetic separation column and the ordinary magnetic separation column are compared.Under the same operating parameters, compared with the ordinary magnetic separation column, the concentrate grade of both is about 68.50%, but the concentrate iron recovery rate of variable diameter magnetic separation column is 2.53 percentage points higher than that of ordinary magnetic separation column.The analysis of concentrate particle size shows that the recovery effect of the variable diameter magnetic separation column on the -0.074 mm particle size is better.