In design stage, the ultimate load of crane steering rod system, as input of finite element analysis to check the structural strength, is almost obtained from spot turn case, but there exists members bending or fracture. Taking a certain type of all-terrain crane as an example, the crane dynamics model under different levels of road surface is established based on MATLAB and ADAMS. The experimental data are fitted to obtain a simplified model of the “magic formula”, which was used as the input condition of the dynamic model to measure the dynamic load of the steering tie rods under two kinds of road surfaces. The load curves show that the ultimate load of the steering tie rods under driving steering condition is larger than that under in-situ steering condition, therefore, the ultimate load under driving steering condition should be used as the input for steering rod system strength checking.