This study, a basic study to improve aerodynamic characteristic of a wind blade, explored through CFD how much the lift to drag ratio improves according to the shape of groove formed on the surface of airfoil NACA0015. This study found out that the ratio improves by 8.7% when the ratio between boundary layer(${delta}$) and the depth of groove(h), the ratio between the depth of groove(h) and the width of groove(d) and the ratio between the length(p) from one groove to the other and the width of groove are 1.1, 0.1 and 1.2 respectively. The number of grooves is two. It was also confirmed that the improvement of the lift to drag ratio is maintained after certain angle of attack.