A method for enlarging the particle diameters of sulfuric acid mists in waste gas and collecting the sulfuric acid mists in high efficiency is provided. A process for disposing waste gas containing sulfur oxides that introduces the waste gas in dry type electrostatic precipitator to remove dusts and then introduces the waste gas in a wet desulfurization apparatus to carry out desulfurization, wherein the waste gas temperature of a smoke channel at a more upstream side than the wet desulfurization apparatus is measured, the flow channel length is variable based on the measurement value of the waste gas temperature, the waste gas is flown to a flow channel means that is adjusted at a channel length capable of cooling the waste gas to the dew point of acid by heat release and then, the waste gas is introduced into the wet desulfurization apparatus.