Abstract: A new sliding backstepping control for helicopter using nonlinear disturbance observer is proposed. Nonlinear disturbance observer (NDO) is used to observer the uncertainties and disturbance of the system. The nonlinear disturbance observer is in exponential convergence by selecting the design parameters. Sliding backstepping controller is designed for the system with nonlinear disturbance observer. The chattering of sliding mode control is reduced. The proposed controller can guarantee stabilization of the closed-loop system. Systems performance is improved. Finally, a computer simulation example is presented to illustrate the effectiveness and the applicability of the suggested method.