A method and apparatus for cleaning waste gas is disclosed. In a sealed casing, there are a partition to divide the internal cavity of said casing into a waste gas cleaning region and a liquid-gas separating region and the blades wheels and airflow guiding plates in the waste gas cleaning region. Its method includes such steps as pumping waste gas in its cleaning region to force the blade wheels to rotate atomizing the cleaning liquid by the blade wheels, contacting the waste gas with the atomized cleaning liquid to dissolved the toxic substances in the cleaning liquid, gas-liquid separating, and exhausting clean gas.