Abstract: To solve the problems of electro-hydraulic servo systems that are nonlinear and have parameter uncertainty and external load disturbances, we propose a new control strategy, called extension-adaptive proportional-integrate-differential (PID) control. This control strategy comprises a PID controller and an extension extrapolator that contains modules such as characteristic variable drawing, correlation function calculation, characteristic mode partitioning, and strategy reasoning. Based on the characteristic modes and control requirements, the system uses switch-control and adaptively adjusts the PID parameters. To evaluate its practical application performance, we applied the extension-adaptive PID controller to an electro-hydraulic position servo system, and the simulation results show that the control strategy satisfies the control requirements and demonstrates good tracking performance and strong robustness, and can effectively transform the control status.