The conductive bearing greases were prepared by adding different conductive materials into polyurea base grease,and their conductive properties in ball bearing were evaluated by the volume resistivity test method and the dynamic breakdown voltage test method of greaselubricated bearings.The results show that the dynamic breakdown voltage test method of greaselubricated bearings is more suitable for the evaluation of the conductive characteristics of the conductive bearing grease.The breakdown voltage of grease decreases with the increase of the amount of conductive material added,and different conductive materials have different conductivity efficiencies.The low breakdown voltage is accompanied by the low breakdown current,and the discharge power is also lower compared with the high breakdown voltage.There is a “conductive ring” phenomenon in the dynamic conductivity test of grease lubricated bearings.After the lubricating film is broken down,the lubricating film is still in a conductive state even if the voltage is reduced.The area of the conductive ring can be used to evaluate the conductive performance of the greases,The smaller the area of conductive ring,the better the conductivity.