Abstract: The dynamic torsional damping characteristics were studied first. The dynamic torsional damping characteristics in vehicle powertrain is the important cause of the self excited vibration. The division of lubricating forms by Stribeck curves was analyzed. The application in vehicle engineering practice was discussed. The approximate formulae for calculating rolling friction coefficient were obtained on the basis of energy theory on the condition that the materials of rolling pair is the same or different. The results showed that rolling friction coefficient or force depends on variable load, viscosity of lubricating oils and sliding velocities. On the basis of the EHL theory, specific film thickness ratio was calculated, and lubrication status was analyzed. The friction damping of the shaft and the lubricant damping of the friction parts increase with the amplitude of the self excited vibration. It acts as the controlling part of the self excited vibration.