The traditional steering knuckle durability test bench can only carry out uniaxial loading test, which cannot fully simulate the stress state of steering knuckle under actual road conditions. To solve it, a durability test system for steering knuckles simulating real-time road conditions and four-axis loading was proposed. Firstly, the three-dimensional model of the mechanical part of the test system was constructed, column strength is calibrated and the key hardware was selected. Then, the modal analysis is carried out by ANSYS Workbench, and the first six modes and natural frequencies of the test system are obtained. Through theoretical calculation, the external excitation frequencies transmitted by the tire to the steering knuckle are 8.47 Hz and 104.4 Hz, which are not consistent with the inherent frequency of the mechanical subsystem system. This verifies that the test system does not produce resonance in the standard loading frequency range. Finally, the experimental system was built and tested.The collected data were subjected to FFT spectrum analysis by using MATLAB. It is concluded that the maximum error of loading force is 0.95 kN, far less than the maximum allowable error of ± 2.5 kN, and the average error of frequency is 1.35 %. The results show that the performance of the steering knuckle durability test system meets the requirements and can simulate the actual working conditions, which provides a reliable theoretical basis for the steering knuckle durability test.