In order to study the effect of impact load on lubrication characteristics of rolling-sliding bearings,a wheel flat system was designed to simulate the cyclic impact load on bearing,the lubrication characteristics of rolling-sliding bearings under impact load and the influence of different working conditions on the lubrication of the roller of rolling-sliding bearings were studied by numerical analysis method.The results show that the influence of impact load on the roller lubrication of rolling-sliding bearings is less than that of rolling bearing.Before the action of impact load,there is a second peak pressure on the roller lubrication film of rolling-sliding bearings which is higher than the central pressure of the oil film,and there is obvious necking at the outlet of the oil film.With the increase of impact load,the second peak pressure will decrease gradually,but it will not disappear.The larger the impact load frequency,the larger the minimum oil film thickness.The bigger the impact load amplitude,the thinner the roller oil film thickness.The thickness of oil film will increase with the increase of lubricating oil viscosity and rotational speed.