An illuminating device comprises a base, a light source and at least one first layer, wherein said light source is assembled on said base to emit a first color temperature light, while first layer is located on the base along the first light irradiation path. The first light is passed through the first layer to react with said first layer to form a second color temperature light for emission, wherein said first color temperature is ranged from 2800K to 20000K, while excitation wavelength range of said first layer is mainly beyond the wavelength of ultraviolet lights for further adjusting the second color temperature range.