For the uncertainty of the external disturbance in the experiment of three degrees of freedom (DOF) helicopter, a semi physical simulation experiment of three DOF based on the robust control method is designed. The control law is designed by using the robust control method according to the establishment of the dynamic model of the three-axis attitude motion and used for simulation experiment. The robust control program is applied in the helicopter, and H∞ control theory is used to design the robust control algorithm in the semi physical simulation experiment. The experimental results show that the stability control of the helicopter attitude is achieved in both simulation experiment and hardware-in-the-loop simulation experiment, and the robust control algorithm can make the attitude control system be stable and meet the expected requirement even when the uncertainty of the system model is exist and the external disturbance is not clear.