An optical coupling element, for coupling a light emitting element to a light transmission element, includes a light guide element. The light guide element has a light incident part, a total reflection surface and a light output part. The light incident path is formed at the light incident part corresponding to the light emitting element. The light reflection path is formed at the light output part corresponding to the light transmission element. The first included angle θ1 is formed between the light incident path and the total reflection surface and is not equal to 45 degrees. The light emitting element is adapted to emit a beam toward the total reflection surface along the light incident path by passing through the light guide element from the light incident part. Moreover, the beam is reflected by the total reflection surface and is outputted toward the light transmission element.