Research on folding-wing aircraft is expanding in global research field. General aircraft shows characteristic of single optimum aerodynamic performance in executing missions. Folding-wing aircraft adapts to multiple-mission flight because aerodynamic performances can be changed if wings are folded or extended. This paper designed a folding-wing aircraft and used Computational Fluid Dynamics (CFD) simulating results to analyze the aerodynamic performance. The CFD simulating results indicate that the stalling angle, diving performance, aileron efficiency, longitudinal stability and controllability, lateral stability and controllability are affected strongly by the folding angle. The stalling angle of attack becomes large and the plane dives quickly if the wings are folded.