A lamp device includes a lamp housing, a light emitting component serving as a heat source and a cooling system. The cooling system includes a liquid coolant, a cooling module, a vapor conduit, a coolant conduit, and a condenser. The cooling module includes a casing and a converting component. The casing has a thermal-transmittance wall having an interior surface and an exterior surface, a coolant inlet and a vapor outlet. The converting component divides an interior of the casing into a coolant chamber and a vaporization chamber. The converting component is formed with a plurality of orifices for permitting the liquid coolant in the coolant chamber to be ejected therethrough to form plumes of the liquid coolant that travel toward the interior surface of the thermal-transmittance wall and that exchange heat with the thermal-transmittance wall to result in coolant vapor flowing out of the vaporization chamber via the vapor outlet.