Fretting behaviour have been investigated in oil lubrication, covering a large range of amplitude from 2 to 400μm. Two types of oil and contact pair on fretting behaviour were studied. A significent reduction in the coefficient of friction occurred above critical displacement amplitude. Analysis of fretting condition in combination with fretting mark examinations reveal that, at an early stage, fretting behaviour depended upon oil boundary lubrication, and was later closely associated with the degree of oxygen access and penetration of oil into the interface. Compared to dry conditions, a great difference in fretting regime behaviour and contact wear was observed.