Abstract ¡@¡@The motion when two parting in machine into contact can combine squeeze and sliding motion. This situation does occur for example in the meshing of gear teeth and in heavily loaded rolling elements bearing etc. In this study, the experiment is used to investigate the microscopic mechanism of the oil film under the combined squeeze and sliding motion. ¡@¡@The laser optical system is employed in the starting friction tester to measure the film thickness accurately by the principle of optical interferometry. High-speed video camera with the microscope records the dynamic characteristics of lubrication in the diminutive contact region. ¡@¡@Results show that the dimple becomes deeper with increasing squeeze velocity. When sliding velocity increases, the duration of dimple becomes shorter, but when the squeeze load increases, the dimple can keep longer. Furthermore, the dimple diameter increases with increasing the curvature radius of steel ball at the same experiment condition.