Abstract: A light emitting device comprising a reflection cap, a substrate, a light source, a first wavelength transformation layer, a second wavelength transformation layer, a cover and a reflection device is provided. The substrate is disposed on the reflection cap. The light source is disposed on the substrate. The first wavelength transformation layer disposed on the substrate surrounds the light source. The second wavelength transformation layer disposed on the substrate surrounds the first wavelength transformation layer. The cover is fixed on the reflection cap. The reflection device comprises a reflection angle adjustment mechanism and a reflector. A ratio of the light reflected by the reflector to be incident on the first wavelength transformation layer to that being incident on the second wavelength transformation layer is adjusted through the angle adjustment of the reflector by the reflection angle adjustment mechanism to generate light with different color temperature.