An illumination device with a fire-fighting function includes a transparent hollow casing, fire-fighting water, a light-emitting unit, and a light-guiding unit. The transparent hollow casing has a receiving space. The fire-fighting water is filled into the receiving space of the transparent hollow casing. The light-emitting unit has a plurality of light-emitting elements disposed beside one or more lateral sides of the transparent hollow casing. The light-guiding unit is disposed over the transparent hollow casing. Hence, when fire accident happens, the transparent hollow casing will melt and crack due to the developed over-heat, and the fire-fighting water is sprayed out from the receiving spaces in order to extinguish one part of flames. Therefore, the present invention can be used as a lighting device or can be used as a fire-fighting device when fire accident happens.