Abstract: A series of sliding-rolling experiments of a GCr15 steel ball against Cr film on glass plate under lubricated conditions at low speed and light load were conducted on a NGY-6 nano-film thickness measuring instrument. The effects of contact stress, speed of steel ball and sliding-rolling ratio on the friction coefficient and film thickness were investigated accordingly. The results showed that the friction coefficient first increased with the increasing sliding-rolling ratio, and then reached a steady state at a fixed contact stress and speed of steel ball. And the film thickness was nearly indepenent on the sliding-rolling ratio at large sliding-rolling ratio. The friction coefficient increased gradually with the increasing contact stress and decreased gradually with the increasing ball speed when the slid-roll ratio was fixed. The film thickness increased gradually with the increasing contact stress and decreased gradually with the increasing ball speed. In the EHL regime, variation of the friction coefficient against the contact stress was slightly while it was large in the thin film lubrication regime. The friction coefficient and film thickness were at a steady state in the thin film lubrication regime when sliding-rolling ratio varied from 0.1 to 0.5.