High-speed bearings are crucial components of the drive motors for new energy vehicles, capable of exceeding 20,000 r/min, Dn ≥ 7 × 106. When the bearing rotates at high speed, the motion instability will cause torque fluctuation, increased friction and wear, increased noise and other problems. Therefore, it is necessary to study the high-speed bearing test system to evaluate the performance. In this paper, the shaft system structure for direct drive of high-speed electric spindle is designed, which can realize the speed change of 0–20,000 r/min within 6 s, and simulate the actual acceleration and deceleration conditions. The electric servo loading method is adopted to simulate axial and radial loads, with a maximum of 5 kN and 12 kN, respectively. The high and low temperature testing system is built to simulate operating environments ranging from −55 to 160 °C. A high-speed bearing testing system is developed, optimizing sensor layout to measure key physical parameters during testing. Through the above methods, the simulation of rotational speed, load and ambient temperature is realized. The deep groove ball bearing EV6206E/2RZTN/C3 is tested. The results show that under the axial load of 195 N, radial load of 1365 N and 90 °C high-temperature environment, bearing speed in the 2000–6000 r/min variable speed conditions, the temperature rise of the bearing is 5.2 °C and the vibration peak value is 3.36 g. During the rapid acceleration and deceleration cycle of the bearing speed at 6000–20,000 r/min, the temperature rise of the bearing is 40.5 °C after 1100 cycles, and the vibration peak value is 8.27 g.