The invention discloses a pesticide production line waste gas purification device, which comprises a shell, an odor controller and an exhaust fan, the shell is provided with an inner cavity, an air inlet is formed in one end of the inner cavity, and a first air outlet is formed in the other end of the inner cavity; a deodorizing liquid washing section, a dewatering and demisting section and a composite photocatalysis section which are sequentially arranged from the air inlet to the first air outlet are arranged in the inner cavity; the deodorizing liquid washing section is used for spraying deodorizing liquid to the gas so as to remove stink particles in the gas; the dehydration and demisting section is used for removing water vapor in the gas so as to intercept floccules in the gas; the composite photocatalysis section is used for decomposing or oxidizing malodorous molecules in the gas; the air inlet end of the odor controller is communicated with the first air outlet; the exhaust fan is used for enabling gas to enter the inner cavity from the gas inlet and sequentially pass through the deodorization liquid washing section, the dehydration and demisting section, the composite photocatalysis section and the odor controller. According to the invention, dust and various malodorous molecules in the waste gas can be removed, so that great pollution to the surrounding environment and the factory environment is avoided.