As the existing unmanned helicopter models are of high order and great load change,a control methodbased on the adaptive dynamic surface approach is proposed.In this method,first,one-order linear filters are usedto estimate the time derivatives of virtual control signals,thus significantly simplifying the design of the controller.Then,an on-line adaptive law is used to estimate the helicopter mass,thus guaranteeing the stability of the closedloopsystem with variable load.Finally,the semi-global uniform bound of tracking errors is proved based on theLyapunov stability theory..Simulated results indicate that the proposed method is effective and feasible.