In this paper, the adaptive model-following control theory, applied to position control of a hydraulic servomechanism is first presented. Second, a digital adaptive model-following PID controller is implemented on a PC-based computer with Delphi 6.0 software. The simulated and experimental results show the performance of the PID controller with and without the adaptive model-following control effects. The model showing following effects on position control shows that the performance of the PID controller can be improved by a suitable adaptation signal.