Abstract: A lighting device includes a first cover, a heat dissipating structure, and a lightbar device. A plurality of first guide slots is formed on the first cover. The heat dissipating structure is disposed in the first cover and has a plurality of heat dissipating fins. A plurality of second guide slots is formed on positions between adjacent heat dissipating fins respectively corresponding to the plurality of first guide slots. The lightbar device is disposed on the heat dissipating structure. Light generated by the lightbar device is emitted out of the first cover. Liquid is drained out through at least one of the plurality of first guide slots and the corresponding second guide slot.