The invention provides a device for evenly dispersing gas into microbubbles in liquid. The device comprises a container and a pored retaining net arranged at the bottom of an inner cavity of the container. A gas injection cavity is formed between the pored retaining net and the bottom wall of the container. The container is filled with a purification solution. A bulk solid stacking layer formed by stacking of a plurality of round bulk solids is arranged on the upper side of the pored retaining net. A bulk solid retaining net is arranged on the upper side of the bulk solid stacking layer. A gas inlet pipeline is inserted into the container, and sequentially penetrates the bulk solid retaining net and the bulk solid stacking layer from top to bottom to be connected with the pored retaining net. Air or waste gas with dust is blown into the gas injection cavity at the bottom of the container through the gas inlet pipeline, diffuses to the upper side, and is fully crushed into the microbubbles after passing through the bulk solid stacking layer; the microbubbles disperse into the purification solution to be purified. By the device, the problems of insufficient gas-liquid exchange, easiness in blocking and high treatment energy consumption in existing dust-polluted air and gas treatment technologies can be solved.