The present invention relates to a lighting device with switchable day/night illumination mode, comprising: a main controlling unit, a driving unit, a lighting unit, a light filtering unit, an illumination mode switching unit, and a power management unit, wherein the lighting unit is coupled to the driving unit and has a plurality of light-emitting devices, moreover, the main controlling unit is used for controlling the driving unit, so as to drive the lighting unit output a visible light; In addition, the illumination mode switching unit is used for controlling the light filtering unit to show and cover the light-emitting surface of the lighting unit, so as to filter the visible light and make the visible light become a visible light with a specific wavelength; wherein the visible light with specific wavelength causes the smallest excitation to human sympathetic; Thus, using the visible light with specific wavelength as illumination light when night can not only assist users in reading, but also avoid from exciting users' sympathetic and causing melatonin suppression.