Abstract: The electro-hydraulic servo system is widely used in industrial production, aerospace, mechanical manufacturing and other fields because of its advantages of high power-to-weight ratio, fast response, high rigidity and low maintenance costs. It also plays an important role in the static/fatigue strength test of aircraft structure. However, the complex physical characteristics of electro-hydraulic servo system make it difficult to establish an accurate dynamic model, which brings great challenges for controller design. In this paper, considering the modeling uncertainty of electro-hydraulic servo system, based on the state space equations of the system, an adaptive robust controller is designed by using the back-stepping method to estimate adaptively and update online the modeling uncertainty in the whole control process. Finally, a series of simulation tests are carried out on the established simulation platform. It is demonstrated that, compared with the PID method, the proposed adaptive control method has faster response speed and higher control accuracy during the control process.