The invention relates to a waste gas treatment device, specifically to a landfill odor collection treatment device. The landfill odor collection treatment device comprises an ozone generation mechanism, a water supply tank, an ozone-solution mixing pool and an ozone reaction chamber, wherein the ozone generation mechanism and the water supply tank are respectively connected with a gas-liquid mixing pump through a pipeline; the outlet of the gas-liquid mixing pump is connected with the ozone-solution mixing pool; the outlet of the ozone-solution mixing pool is connected with a catalyst addition chamber; a stirring unit is arranged inside the catalyst addition chamber which is connected with a spray pipe through a water pump; the spray pipe is arranged at the top part of the interior of the ozone reaction chamber; spray heads are distributed on the spray pipe; the bottom part of the ozone reaction chamber is provided with an odor inlet; and the top part of the ozone reaction chamber is provided with a gas outlet. The device utilizes the ozone generation mechanism to generate ozone which is mixed with water, and an ozone catalyst is added, so ozone treatment effect is improved; the device has simple structure and is convenient to operate; meanwhile, equipment is insusceptible to corrosion; and treated waste gas is free of odor, and can be discharged up to standard or comprehensively utilized.