The invention discloses a device for accelerating aerobic denitrification. The device comprises a reaction pond, wherein the reaction pond is internally provided with a round separated drum, wherein the round separated drum is internally provided with a V-shaped conical drum and an inverted-V-shaped conical drum in sequence from top to bottom; the V-shaped conical drum and the inverted-V-shaped conical drum are communicated; a stirring machine and a submersible pump are arranged at the connecting position of openings of the V-shaped conical drum and the inverted-V-shaped conical drum; a water feeding pipe of the device penetrates through the wall of the reaction pond and the wall of the round separated drum to be led into the inverted-V-shaped conical drum; double layers of grid frames are arranged between the round separated drum and the V-shaped conical drum; combined fillers are added between the double layers of grid frames; and suspended ball fillers are added in the V-shaped conical drum. According to the device disclosed by the invention, by utilization of the round separated drum, the V-shaped conical drum and the inverted-V-shaped conical drum, the inner part of the reaction pond is divided into a plurality of reaction chambers, waste water is treated respectively by an active sludge method, a biofilm method, 'fluidized bed' and film formation of 'fixed bed' to accelerate aerobic denitrification in the plurality of reaction chambers, and organic compounds are degraded into simple inorganic matters, so that the denitrifying effect is achieved and the treating effect is excellent.