Abstract: The running in behavior of several corrosive running in agents was examined on BJ52A adhesion test machine, JP BD1500 contact fatigue test machine, and CL 100 gear test machine. The mechanism of the running in agents was investigated as well. It was found that after running in with corrosive running in agent, the surface roughness decreased remarkably and the surface contact area increased greatly. Full load running in was also realizable. Compared with the running in behavior of abrasive running in agent, no hard abrasive embedded into the running in surface thus the surface contact precision was improved remarkably and the developing of crack source was decreased. The load carrying capacity of the surface was improved greatly as well. The corrosive running in would find promising application in decreasing gear surface roughness and increasing surface contact precision.