In this paper, the adaptive model-following control theory applied to the position control of the hydraulic servomechanism is first presented. Second, the digital adaptive model-following PID controller is implemented on the PC-based computer with the Delphi 6.0 software. Both the simulation and experiment are used to investigate that the characteristics of the PID controller with and without the tracking effect of adaptive model-following control. The model following effects on the position control show that the servo performances of the PID controller can be improved by a suitable adaptation signal.