The invention discloses a back support bracket of a motorcycle, which comprises an inner bend bracket (1), wherein the front end of the inner bend bracket (1) is provided with an installing hole (2a) which is connected with a motorcycle frame, the two sides of the inner bend bracket (1) are respectively provided with a supporting ear (3), the supporting ears (3) are arranged under the inner bend bracket (1) and are vertical thereto, the supporting ears (3) are provided with installing holes (2b) which are connected with the motorcycle frame, the middle back part of the inner bend bracket (1) is provided with a connecting and supporting hole (4), and the back end of the inner bend bracket (1) is provided with a back mudguard installing point (5). The back support bracket has the benefit effects of not only being capable of being taken as an installing platform of a back mudguard, a back goods bracket and the like but also being capable of increasing the intensity of the back mudguard.