Abstract: A waste gas-purifying device including a primary dust-collecting assembly, a first stage fan assembly, a second stage fan assembly, a filtering means and a water tank, wherein the waste gas discharged from a plant is sucked by the rotating fans and flows into the primary dust-collecting assembly to be divided into three ways of flows which respectively enter three fans of the first stage fan assembly, a shaft of the fan being hollow and formed with multiple holes with different diameters and directions whereby water vapor is injected from these holes to mix with the dust particles in the waste gas and then the water together with the dust drops down and flows into the water tank to be transferred by a rotary coil rod toward the ground surface for further processing, the waste gas being further forced into the filtering means by the pushing force of the fans and sucking force of a pump and then discharged from the filtering means and flowing into a dividing pipe which extends below the water surface of the wat