The largescale wind turbine blade contour design and the choice of wing section are the core technology in wind power generation; both of them could affect the wind turbine performance and the energy efficiency. This paper presents the redesign principles and methods for largescale wind turbine blade, based on the analysis of blade CAD model from reverse engineering, looking for geometric features, exploring basic constraint factors on blade shape, and determining parameters of blade cross section calculation formula. Blade design has been completed by using this selfdeveloped blade airfoil automatic generation system. The results showed that the redesign meets all the production requirements.