The work aims to enhance the cultural connotation of urban rail train appearance design and enrich the cultural representation methods for industrial design of urban rail trains. With Chengdu shadow puppet culture as an example, based on the synaesthesia translation theory, the transformation and translation of the information received in the user's multi sensory image activities were realized by constructing the correlation attribute of "synaesthesia bridge", and the translated modeling language was analyzed by cluster analysis combined with analytic hierarchy process (AHP). Finally, starting from the user decoding path, the scientificity of the train modeling language was inversely verified. Seven indicators of proprioceptive imagery were calculated and weighted:shadow figure local features, shadow figure image, shadow figure colour, shadow light gradient, shadow carving texture, shadow texture and shadow figure contour line. Applying the above methods to the appearance design practice of urban rail trains forms an appearance scheme of urban rail trains expressing the cultural image of shadow play in Chengdu and provides new ideas for urban rail trains with regional cultural integration. It has a certain reference value.