Magnetic fluid has many advantages when serving as lubricant. With an appropriate magnetic field this lubricant can prevent leakage and increase the load capacity of lubricant film. It can also be fixed at the friction zone by applying an external magnetic field. This paper aims to improve the lubrication performance of friction pairs under alternating magnetic fields. The test was conducted on a NG-x reciprocating friction tester. Test results using the magnetic fluid and those using expanded graphite were compared. The tribo-surfaces were obtained in real time. It is concluded that the magnetic fluid lubricant has better lubricating property than the nonmagnetic lubricant (expanded graphite) because it can cling on friction pairs uniformly, and the endurance magnetic fluid lubricant is better than that of nonmagnetic lubricant.