The invention discloses a hybrid power tractor brake system with a retarder. The hybrid power tractor brake system with the retarder comprises an engine, a clutch, a motor, a transmission, a retarder, a retarder handle, a hybrid power controller, an air cylinder, a brake valve, a first gas pressure sensor, a second gas pressure sensor, an electric valve, a brake chamber and a brake pedal which are arranged on a tractor, wherein the engine is connected with the motor through the clutch, the motor is connected with the transmission, the transmission is in serious with the retarder, the brake pedal is connected with the brake valve, the air cylinder , the brake valve, the electric valve and the brake chamber are sequentially connected through a pneumatic pipeline, the first gas pressure sensor is mounted in the pneumatic pipeline at the rear of the brake valve , and the second gas pressure sensor is mounted in the pneumatic pipeline at the rear of the electric valve. The invention further discloses a control method of the hybrid power tractor brake system. The hybrid power tractor brake system can recycle brake energy as much as possible while meeting brake requirements of a driver, and thus oil consumption of the whole tractor is reduced.