The SST turbulent flow model was used to simulate the dynamic sinusoidal oscillation aerodynamic characteristics of S809 smooth surface airfoil. A comparison with the test data measured from the wind tunnel in Ohio State University shows that the simulation results are in good agreement with the test ones,proving that the method in question is feasible and effective. The dynamic aerodynamic characteristics of S809 airfoil at various levels of roughness were numerically simulated when it was being pitched and oscillated,during which the hysteresis loop of the lift and drag coefficient was obtained. It has been concluded from an analysis that for the dynamic aerodynamic characteristics of the airfoil,the critical roughness is regarded as 0. 4 mm. Furthermore,the dynamic aerodynamic characteristics of the airfoil were simulated and analyzed when the rough band having a roughness of 0. 4 mm is located at various places on the pressure and suction surface of the airfoil. It has been pointed out that the dynamic aerodynamic characteristics of the airfoil are most susceptible to the rough band being located at the place of 10% away from the leading edge on the suction surface. With an increase of the height of the rough band,the dynamic aerodynamic performance will deteriorate by a big margin and the dynamic stall attack angle will be in advance.