The invention discloses a sewage treatment device for a large-scale sewage treatment station. The sewage treatment device comprises a filtering device, a regulating hydrolysis tank, a grade-A biochemical tank, a grade-O biochemical tank, a precipitation tank, an improved coagulation system, a disinfection tank, a sludge thickening tank, oxygenation equipment and a gas stripping device, wherein the filtering device, the regulating hydrolysis tank, the grade-A biochemical tank, the grade-O biochemical tank, the precipitation tank, the improved coagulation system and the disinfection tank are connected with one another in sequence from front to back; the gas stripping device is a pulse gas stripping device which is used for stripping one part of sludge precipitated in the precipitation tank into the sludge thickening tank, and the other part of the sludge precipitated in the precipitation tank into the grade-A biochemical tank; the grade-O biochemical tank is provided with the oxygenation equipment which is a centrifugal blower. The invention also provides a sewage treatment method for the large-scale sewage treatment station. The sewage treatment device disclosed by the invention has the advantages of being full in filtration and high in treatment efficiency of precipitated sludge, saving the floor area, and having an integrated function of regulation and decomposition.