The invention discloses a four-degree-of-freedom helicopter dynamic flight simulator. Simultaneous simulation of three modes of space yaw, rolling and pitching can be achieved under the centrifugal field, and overload simulation is achieved; mounting components on a rotating arm are arranged in a centralized manner, a balancing design method is adopted, a counterweight unit is designed according to the trimming principle and mounted on the rotating arm, the mass center of the dynamic flight simulator is placed on the revolution axis, and vibration of the simulator caused by imbalance is reduced. The asymmetric rotating arm structure is adopted to reduce the rotational inertia of the dynamic flight simulator, and energy consumption of the dynamic flight simulator is reduced; a transmissionunit is adopted to prevent vibration of a main reduction motor from being directly transmitted to the rotating arm to make the entire dynamic flight simulator vibrate excessively, the unbalanced forceof the rotating arm and the rotating arm mounting components is transmitted to the civil part through the transmission unit, and running stability of the main reduction motor is enhanced.