Perforated composite panels are widely used in many engineering applications as subcomponents of complex structures including aircraft, ships, and other transport vehicles. In many of these applications, the primary objective of using the panel is to resist buckling. In this present study, a finite element analysis is performed adopting popular commercial software code Ansys on the buckling behavior of a simply supported quasi-isotropic symmetric composite panel with central circular cutouts, reinforced with stiffeners on both sides of the cutouts under uniaxial, biaxial and combined loading conditions. The main objective is to achieve the elastic buckling response of the perforated composite panels considering some important aspects of the stiffener as follows: (1) effect of the presence of reinforcement, (2) effect of stiffener area, (3) effect of stiffener thickness, (4) effect of stiffener material and (5) effect of fiber orientation angle. It is observed that reinforcement can significantly improve the critical buckling load of a panel, which is already reduced due to cutouts. Then, increasing the area of the stiffener does not have a major impact on the buckling stability of the panels. However, increasing the thickness can play a crucial role to strengthen the buckling stability. Finally, it is found that in comparison to aluminum and titanium alloys, epoxy-carbon is more practical as a stiffener material with correct fiber orientation angle (90°), considering the low weight increment and higher buckling achievability.