To solve the problem of low lift to drag ratio of Magnus cylinder airfoil, the Computational Fluid Dynamics software Fluent was used to study the principle of a drop of the drag force of cylinder when rotating. And the principle was used to further reduce the drag of rotating cylinder. A traditional airfoil head and a triangle tail was used to study the effect of the aerodynamic performance change of the combined airfoil. A conclusion was made that with a suitable profile of the tail would reduce the drag force of the combined airfoil thus increase the lift to drag ratio of the airfoil. At last an orthogonal test was made to determine the size of the tail airfoil. The result show that the optimized airfoil reduce the drag force to 50% of the original cylinder and improve the lift to drag ratio to 50%.