The smoke exhaust pipe of the store cannot be directly connected to the smoke exhaust main pipe of the mall. In the smoke exhaust system of multiple restaurants, each restaurant is connected to the public smoke exhaust pipeline through a smoke exhaust branch pipe, and each restaurant is respectively provided with a range hood and an oil fume purifier. There is a check valve at the joint between the smoke exhaust branch pipe of the restaurant and the public flue. Due to the high pressure in the public flue, restaurants interfere with each other, and the lampblack in the restaurants cannot be discharged into the public flue smoothly.