The multi-body dynamics simulation and physical iteration were carried out based on the 4-channel road simulation bench, the solution of fatigue test bench which was suitable for cab with frame and suspension was designed. Large load and displacement above the suspension can be loaded on the test bench, and the same weak position of cab exposed on the road test can be assessed well on the fatigue test bench. The effectiveness of the bench test solution was verified though comparative study. And it has important reference for the same type of cab assembly with suspension in the fatigue bench test. According to the durability specifications of cab assembly, a multi-body dynamics model with a satisfactory accuracy was built. And the fixture check and virtual iteration analysis were used to verify the effectiveness of the solution. According to the road load signal analysis and multi-body dynamics analysis results, the test bench with linear guide and spherical joint was built. In order to get the driving signals of cylinders, the acceleration signals beside the suspension were used as the target signals for physical iteration. The best test bench solution is the linear guide installed on the back and the spherical joint installed on the bottom of front cylinders through comparing three different iteration result of test bench solution. As a result, after completing 11 different road sections of iterations, the RMS error of target signal substantially was less than 13%. In order to simulate the actual condition, the driving signals obtained by physical iteration were used to drive the cylinder. Through comparative study, the test results of fatigue bench test and proving ground test has a highly consistency in terms of the damage distribution. Through the secondary development of 4-channel road simulation bench, it is efficient and accurate to assess the durability performance of the cab assembly with suspension. And it also provides guidance for developing and designing a test bench of functional diversification.