Abstract
The article researchs on building models and simulating the dynamics of hydraulic steering system on the motorized graders. The building of a dynamical model of hydraulic steering system is made from building a model of the assembly in the system including swing valve, safety valve, diverter mechanism, oil pipeline, steering cylinder,... to build the system model. The process of simulating the dynamics of hydraulic steering system on the motorized graders is to survey the real work of the system to efficiently exploitation and use of the graders.