The invention discloses a preparation system of quick numerical control machining of complex parts of an airplane and a method. The system takes the existing CAD / CAM system as a platform, and comprises a technology resource and knowledge base management module, a quick blank generation module, a part classification and technical scheme analysis module, an automatic programming module, a quick tool generation module, a strain analysis and deformation control module, a front and rear process module and a technology data generation module. The system is built on the basis of a three-dimensional numeric part model, systematically and exactly embodies a specialized flow path for supporting the numerical control machining technology preparing and the programming of the complex parts of the airplane, can greatly reduce man-machine interaction operation required by preparing technology and programming, effectively solves the problems of the unstable programmed procedure and the unreasonable scheme design of the machining technology caused by the lack of the experience of process operators, and the like, can effectively control the deformation quantity during and after machining the parts, can obviously improve the efficiency and the quality of the numerical control machining preparing and the programming, and improves the professional level and the intelligence level of the CAD / CAM system.