In this paper,an impedance composite control method based on disturbance observer is proposed for manipulator system with unknown disturbances.For tracking the second order impedance dynamic model,a composite control strategy is designed,which includes the disturbance observer (DOB),the impedance controller,and the position controller to estimate unknown disturbances,correct input angle,and track the adjusted angle,respectively.This composite control strategy ensures that the impedance error converges to a small neighborhood,thus realizes the desired dynamic tracking of the second order impedance model.The effectiveness of the proposed control method is proved by simulation examples.