Abstract: Based on the fluorescence technique, the influence of surface wettability on the lubricating oil supply was studied with the test rig for measuring hydrodynamic lubrication film thickness in a slider-on-disc contact. In the experiments, the friction pair consists of a stationary slider and a rotating transparent disk. A closed oil pool around the contact region was formed. The results show that the distribution of the lubricant in the oil pool was affected by the wettability of the slider surface under fully supplied condition although the lubricant in the contact area was still sufficient. Under limited lubricant supply condition, the surface wettability of the slider outside the contact area affected the distribution of the oil pool and the supply of lubricant at the entrance of contact area. And the low wettability aggravated the degree of lack of oil in the contact area, which directly led to the decrease of the film thickness. The high surface tension of the lubricant and low adhesion of the disc surface improved lubricant replenishment on the contact track. The dewetting of the lubricant on the surface of the disk led to the discrete droplets, which had a positive effect on the lubricant replenishment on the contact track and the formation of the film thickness.