A　composite　control　method　is　proposed　based　on　adaptive　terminal　sliding　mode　control　and　disturbance　observer　theory　for　a　class　of　high-order　nonlinear　dynamic　systems.　In　this　control　method,　the　disturbance　observer　is　introduced　to　estimate　system　disturbance　and　the　estimated　value　is　used　to　compensate　sliding　mode　controller＇s　outputs　to　restrain　the　unknown　uncertainty.　For　controller　output　chattering　case,　an　adaptive　law　based　on　disturbance　observer　is　designed.　Under　the　adaptive　law,　the　controller＇s　switching　gain　can　be　adjusted　automatically,　which　can　reduce　the　high　frequency　chattering　of　outputs.　The　Lyapunov　theory　is　applied　to　prove　the　stability　of　the　control　method.　Finally,　the　simulation　results　of　an　example　show　the　feasibility　and　effectiveness　of　the　proposed　approach.