Common white smoke in automobiles is mainly divided into white smoke at the engine, white smoke at the cab and white smoke at the exhaust pipe. The common white smoke at the engine is that the cooling water leaks to the heating part, or the oil leakage at the engine drops to the high temperature part, causing water or oil and gas to evaporate; White smoke is emitted from the air outlet of the cab air conditioner because of the high humidity of the environment and the water vapor that appears after evaporation and condensation by the air conditioner; The white smoke in the exhaust pipe is the result of the conversion of engine exhaust gas into hydrate steam by three-way catalysis. Other cigarettes include drivers smoking in cars, cars burning and so on.