The invention discloses a bicycle back brake driving device. A star wheel exceeding a clutch, a pusher dog and a pin roller are arranged on a center shaft, and the star wheel and a driving medium areintegrally connected; when the foot pedal is pushed forward, the pin roller moves to the big end of start wheel space so as to achieve exceeding forwarding; when the foot pedal is pushed backward, thepin roller moves to the small end of the star wheel space to achieve bonding, and the driving end tensions a transmission part to achieve retarding braking; when a crank is not properly placed, a left brake handle is slightly pressed to toggle the pusher dog so as to get on/off and brake easily. The foot pedal braking is forceful and convenient; thus, the trouble of pressing the hand brake to break in mountain areas on occasions of large slopes, long slopes, heavy load, emergency braking and cold areas can be avoided. The bicycle back brake driving device has the advantages of simple structure, high durability, few parts and easy assembly, disassembly and repair. Besides, a power supply and electronic elements are arranged in addition to an existing microswitch, thus acousto-optic warningcan be realized on occasions of speed reduction and braking, and power is cut off before an electric bicycle is braked.