The utility model discloses a transmission fatigue life testing device. The transmission fatigue life testing device comprises a test bench and an analysis processing system. The test bench provides driving torque and simulation load torque for the driving motor and the load motor through the power battery. The transmission is mounted between the driving motor and the load motor; the transmissionefficiency of the transmission can be obtained through the input sensor and the output sensor; by arranging the vibration table, the vibration working condition can be simulated; the temperature control box is used for simulating the working temperature of the transmission; the noise sensor is used for testing noise and abnormal sound of the transmission; the multi-tooth gear and the rotating speed sensor are used for testing the rotating speed of the transmission; the analyzing and processing system comprises a printer, a processor and a displayer. The processor receives, analyzes and processes data of the input sensor, the output sensor, the rotating speed sensor and the noise sensor.