Reciprocating rubber seals that aim to prevent fluid leakage between moving parts are critical mechanical components, as extensively used in hydraulic cylinders, pumps, valves, and dampers. The sealing performance, as reflected by sliding friction and oil film thickness, significantly affects the efficiency and durability of these industrial components. However, the lack of effective methods that can measure the variation of sliding friction and oil film thickness distribution remains a challenge for sealing systems research and design. This work establishes an experimental platform that consists of reciprocating motion between O-type rubber rings and glass components at zero pressure difference. In addition to the load cell-measured sliding friction forces, the Laser-Induced Fluorescence (LIF) is developed and applied to enable visualization of oil film thickness distribution under varied loads and frequencies, with the thickness measurement resolution down to 10μm" role="presentation"> 10 μ m . Despite the viscoelastic characteristics of rubber materials, the simultaneous friction and oil film thickness measurement results essentially correspond to the classical Stribeck curves, as observed in metal-to-metal contact. Furthermore, the LIF measured contact width between the rubber and the glass plate is verified with experimental data closely aligned with the Hertz contact theory. These findings underscore the pivotal role of oil film dynamics and contact mechanics in governing seal performance, offering valuable insights for optimizing sealing system design to reduce friction and wear, thereby enhancing operational efficiency and extending service life in engineering applications.