A light transmission system includes a light guide support, a first convex lens, an optical waveguide member, and two second convex lenses. The light guide support includes a first surface, a second surface, a hollow space formed between the first surface and the second surface, and an inner reflecting surface forming an angle of 45 degrees relative to the first surface. The first convex lens is formed at the first surface, and configured for converging light to the inner reflecting surface. The optical waveguide member is located at the hollow space, and includes a main section parallel with the first surface, two first branch sections extending from and forming equal angles relative to the main section, and two second branch sections extending from the respective first branch sections. The two second convex lenses are formed at the second surface and aligned with the respective second branch sections.