Nowadays most general airplanes are still designed using similar methods with middle or large transport aircraft, which means that they use few optimization method, leading to low aerodynamic efficiency and high economic cost. To change this situation, some design features of general airplanes are analyzed and summarized from basic aerodynamic principles, which include two contradictions. Then an effective strategy was put forward for improving aerodynamic efficiency, different with traditional general airplane design methods and middle or large transport aircraft design methods. This strategy presents some new requirements on design methods of new general airplanes. A conceptual optimization design example was used to prove the effectiveness of this new strategy.