Abstract: According to the unique structure features and control characteristics of the miniature ducted fan aircraft, that are situated between helicopters and fixed wing aircraft, the dynamics of the miniature ducted fan aircraft in hovering was analyzed. Based on the theories of rigid body dynamics and aerodynamics, the equations of force and moment acting on the aircraft were deduced and its kinetic model was established. Meanwhile, the zero dynamics of the model and its asymptotic properties were investigated to find the relationship between the aircraft physical parameters and the in-dynamic stability. The results show that the exponent instability of the system zero dynamics would not only be affected by the distance from the pressure center of control flap to the vehicle mass center, but also be related with the gyroscopic inertia of the propeller.