Abstract: The aerodynamic force on circular cylinders changes because of the formation of asymmetric flow when the cylinder rotates. The effect of the rotation on aerodynamic force has wide application in wind power generation or navigation, and the characteristics of the aerodynamic force on a rotating circular cylinder significantly influence the development of these applications. In this study, the features of the aerodynamic force on a circular cylinder are illustrated to reveal the effect of the rotation ratio. The results show that an average lift coefficient increases with the increase of the rotation ratio. Meanwhile, the mean drag coefficient decreases when the rotation ratio increases. The variation of the lift coefficient with the rotation ratio differs from the drag coefficient. The lift coefficient changes more considerably than the drag coefficient.