Abstract: In order to realize the robust design of full hydraulic Steering Control Unit (SCU), based on the bond graph, the dynamic model was established, and the state equation of the SCU was obtained. With the SCU valve core diameter, equivalent rotation inertia, internal total compression capacity as the design variables and the minimum overshoot of the SCU flow response as the design objective, the traditional optimal design of SCU was firstly done, and then with the traditional optimal design result as the initial value, the robust optimal design was done for the SCU. By contrasting and analyzing the dynamic response results based on traditional optimal design and robust optimal design respectively, the robustly optimized SCU structure parameters was more reasonable, dynamic response peak overshoots reduced 12.5% and the robust was improved. Taking the traditional optimal design results as the initial value, the robust design of SCU is practical and effective.