An optical element includes a substrate and an anti-reflective unit provided on one surface of the substrate. The anti-reflective unit includes a first coating layer, a second coating layer, a third coating layer, a fourth coating layer, and a fifth coating layer arranged on the substrate sequentially. The thickness of each of the first coating layer, the third coating layer, and the fifth coating layer is in the approximate range from 6 to 100 nanometers, and the thickness of each of the second coating layer and the fourth coating layer is in the approximate range from 10 to 200 nanometers. The first coating layer, the third coating layer, and the fifth coating layer are made of SiO2, and the second coating layer and the fourth coating layer are made of TiO2. The optical element can provide a high rate of light transmission.