A refractive-index measurement system includes a light source, a first beam splitter, a first reflective mirror, a second reflective mirror, a second beam splitter, a container, a first polarizer, and a second polarizer. The first beam splitter splits light emitted from the light source into first and second light beams. The first light beam and the second light beam are reflected by the first reflective mirror and the second reflective mirror, respectively, incident into the second light beam splitter. The container is positioned along an optical pathway of first light beam. The container accommodates a lens and is filled with a medium having a refractive index substantially the same as a theoretical refractive index of the lens. The first polarizer is positioned along the optical pathway of the first light beam. The second polarizer is positioned along an optical pathway of the second light beam.