Abstract: In this paper, a method of obtaining the fatigue load of light truck cab with simple test and high accuracy is presented. Firstly, the virtual iterative multi-body dynamic model of the cab is established, and the virtual iteration of the cab on the medium and low frequency load is performed. Then the transmission path is analyzed, the driving excitation position is found to be the main influencing factor of the non-convergence, and the iteration model is optimized and improved successfully. The practical application shows that the method can quickly and accurately obtain the cab road load data, effectively support the cab fatigue analysis, the fault recurrence in durable test and fatigue performance optimization in the early stage of body development, and has good engineering application value.