Signal lights, navigation lights and searchlights used in transportation, ships, airport and other applications are vulnerable to be influenced by weather factors. The penetration properties of different color LED light sources in water fog and sea fog were compared by a series of experiments, and the relationship between the transmittance T of LED light sources and distance in water fog was researched. Experimental results show that the transmittance T of all kinds of color LEDs declines exponentially with the increasing of transmission distance in fog; both in water fog and sea fog, the yellow LED has the maximum transmittance compared to other color LED sources. This research work will provide a basis for the design of signal lights, searchlights and other functional illuminating fields.