Abstract: The problem of controlling the motion of flexible manipulator is discu ssed. A simple designing method of controller is developed based on difference e quation and least-mean-square (LMS). If a faster sampling frequency is utilize d, some uncertain terms which are difficult to be characterized exactly can be n eglected, and the system performance can be held. Digital simulation results of single flexible manipulator are given to show that in the closed-loop system pr oposed by this paper accurate trajectory tracking and vibration damping can be a ccomplished.