In this paper the behavior of a flat plate with rotational degree of freedom has been discussed. Because of the mutual influence between rotational plate and airflow, unsteadiness of flow and complexity of vortex flow, there is no proper analytical method resolution for this problem. Also it can't be analyzed by in the numerical solvers based on the Navier_Stokes equations. Therefore, improved Discrete_Vortex method should be used to calculate normal force coefficient and aerodynamic pitching moment. Two modeling were done; free rotation and force rotation. Normal and axial coefficient and aerodynamic moment based on proportion of angle of plate to the flow in steady state and in free rotation and force rotation were calculated. To evaluate the numerical results some experimental test on the plate in wind tunnel were done and the behavior of that plate by experiment method were surveyed. Based on the result, in force rotation regime because of engendering some differential structure in vortex flow (in compare with static position), there are Aerodynamic Hysteresis in normal force and rotational moment that this hysteresis nutritious with decrease in Strohaul number. If any plate with rotational degree of freedom being under the Air flow, may result in being free rotation. This position is occurred when momentary of inertia being between 1.43-5 and angle of attack being little enough. In another values of momentary of inertia, plate enters in free vibration (or damping regime)