Abstract: To solve the problems that it is difficult to model a small helicopter and its internal and external disturbances are large,a flight control scheme is proposed based on active-disturbance-rejection control(ADRC)technique.For the original algorithm,the discrete equation of extended state observer and the nonlinear feedback function are modified to meet the requirements of flight control.Simulation results of taking off,hovering and flying in strong wind validate the efficiency of the modified ADRC algorithm.