A robust composite tracking control scheme was proposed to accomplish accurate trajectory tracking for motor servo systems subject to input saturation and unknown disturbance. The control scheme incorporated a reference generator which constructed the target state vector corresponding with the trajectory reference signal, and an extended state observer which estimated both the system states and the disturbance. The final control law adopted a combination of feedback and feedforward actions. The stability of the closedloop control system was strictly analyzed using the Lyapunov theory. Simulation studies were conducted in MATLAB, followed by an experimental verification on a DSPcontrolled XYtable driven by permanent magnet linear motors. The results indicated that the proposed control scheme could achieve superior transient performance and steadystate accuracy in various trajectory tracking tasks and was more robust against the amplitude variations of target trajectory and disturbance.