With regard to the cultural inheritance and design application of Miao patterns, an innovative design method of ethnic patterns based on extensional representation and neural network is proposed to deconstruct, map, and reconstruct Miao batik patterns. Firstly, Miao batik patterns are characterized by extension, and the divergence tree is used to construct the design growth stage model to expand and analyze the elements of Miao patterns. Secondly, Miao batik patterns are analyzed with Kansei images based on Kansei engineering, proposing a pattern deconstruction method for pattern configuration, pattern semantics and types, with which the deconstructive space of pattern feature elements and the cognitive space of emotional images are constructed. The neural network is used to construct the Kansei prediction model that recommends design elements such as pattern configuration to users in terms of their preference, and the design thinking is converging. Its advantages are verified by the comparison with the linear regression prediction model. Finally, shape grammar is used to refine Miao batik patterns according to the characteristic elements recommended by the model. The method is verified feasible with Miao batik patterns and can provide a reference for the deconstruction and innovative design of other ethnic patterns.