The invention provides a multifunctional 
sewage sedimentation tank and a use method thereof, and belongs to the technical field of 
sewage treatment equipment. The multifunctional 
sewage sedimentation tank comprises a 
precipitation cylinder, a cover plate, a drain outlet, an 
exhaust pipe, a water inlet 
pipe, a water outlet 
pipe, a driving mechanism, a mud scraping mechanism and an opening and closing mechanism, the cover plate is slidably arranged in the 
precipitation cylinder, a 
precipitation cavity is formed between the cover plate and the interior of the precipitation cylinder, the drain outlet is formed in the bottom of the precipitation cylinder, and a first rotating shaft is coaxially and rotatably arranged in the drain outlet; One end of the 
exhaust pipe is fixedly connected to the cover plate, a third one-way valve is arranged on the 
exhaust pipe, the water inlet 
pipe and the water outlet pipe are both fixedly connected to the side wall of the precipitation cylinder, the driving mechanism can drive the first rotating shaft to rotate through vertical sliding of the cover plate, and when the first rotating shaft rotates, the 
sludge scraping mechanism can scrape 
sludge at the bottom of the precipitation cavity into the drain outlet, when the first rotating shaft rotates, the opening and closing mechanism can open and close the drain outlet. According to the invention, organic matters in sewage can be fermented to generate 
biogas, 
sludge at the bottom can be cleaned, and the multifunctional sewage 
sedimentation tank is green and environment-friendly.