A method of manufacturing an organic light-emitting device having reduced ambient-light reflection is disclosed. The method comprises the following steps. First, a metal reflective layer is formed on a provided substrate. Then a transparent anode, an organic layer, a translucent electron-injecting cathode, a buffer layer and a transparent electrode are sequentially deposited on the metal reflective layer. In order to reduce the affect of the ambient-light reflection, adjusting the thickness of the aforementioned layers that the reflected lights generate destructive optical interference and improve the visually perceived contrast of the emitted light.