The invention discloses an integrated formula car diffuser with additional side wings. The diffuser adopting an integrated structure comprises a left-part side wing main wing, a right-part side wing main wing, a left-part side wing flap and a right-part side wing flap, wherein the left-part side wing main wing and the left-part side wing flap are in front-rear arrangement in a manner that an angle a and an angle b are respectively formed between the left-part side wing main wing and a level surface and between the left-right side wing flap and the level surface through a left-part left-end plate and a right-part right-end plate, the right-part side wing main wing and the right-part side wing flap are in front-rear arrangement in a manner that an angle a and an angle b are respectively formed between the right-part side wing main wing and the level surface and between the right-part side wing flap and the level surface through a right-part left-end plate and a right-part right-end plate, and two side wing components, of the diffuser, which are symmetrically arranged, are formed; a left flow deflector and a right flow deflector which are in V-shaped arrangement are arranged between the two side wing components, the left flow deflector and a left surface form a left guide groove, and the right flow deflector and a right surface form a right guide groove. According to the diffuser disclosed by the invention, the downward pressure of the car can be increased, and besides, the centre of gravity of the car is moved forwards, so that understeer of the car is avoided, besides, the impact of air currents on rear wheels of the car is avoided, and the running resistance of the car is reduced.