The invention discloses a high-speed electric multiple unit axle box bearing three-degree-of-freedom dynamic load reliability test platform and aims to overcome a problem that an axle box bearing reliability test can be not carried out in a practical operation. The test platform comprises a torque detection testing device and an axle box bearing reliability test device. The torque detection testing device is connected with the axle box bearing reliability test device through a cross shaft type universal shaft coupler. The axle box bearing reliability test device comprises a simulated frame side beam test device, a three-degree-of-freedom vibration simulation test device and a shaft assembly for an axle box bearing test. The three-degree-of-freedom vibration simulation test device comprises a vibration T type beam and a lateral actuator. The shaft assembly for the axle box bearing test is fixed on the vibration T type beam through bolts. The simulated frame side beam test device and the three-degree-of-freedom vibration simulation test device are placed in a parallel way. The parallel distance of the vibration T type beam in the three-degree-of-freedom vibration simulation test device and a simulated frame side beam supporting platform in the simulated frame side beam test device is 20 mm to 40 mm.