The invention discloses a production device and a production method for synthesizing acetic acid by low-pressure carbonylation of methanol. A fluid stirring device arranged on the production device provided by the invention changes the situation that a mechanical stirring shaft seal and a transmission device are easy to damage in an operation process, eliminates dynamic seal points, and greatly improves the safe and stable operation of a system. At the same time, by matching with a CO distributor, the CO gas distribution in a reactor is more uniform, the gas-liquid two-phase mixing effect is improved, the reaction rate is increased, the reaction state of the system is optimized, and the production capacity of the device is increased from 300,000 tons per year to 600,000 tons per year.