In order to improve the detection efficiency of magnetite powder for coal preparation, the detection method was studied. During detecting magnetic content, the double operation will be transformed into single operation in the operation of the magnetic separator to realize the goal of easy operation, reduced personnel and improved efficiency. The content of magnetic material, -325mesh content of magnetite powder by the wet or dry methods were compared. The results show that the wet method does not need the drying process of magnetite powder, but directly uses the received magnetite powder for test, and then converts it into dry basis for calculation. The test time is shortened from original more than 7 hours to present less than 4 hours, the test time is saved and the work is efficiency greatly increased.