In order to design a light carbody more efficiently and reasonably, the sub-model technology combined with multi-objective optimization based on response surface is used to optimize the structure. Taking an articulated carbody of light railway vehicle as the research object, the static strength analysis of the whole carbody is carried out according to the EN12663 standard. It is found that the end of the car body in the hinged area is under severe stress, and then the sub-modal is created by choosing interested area, and applied boundary conditions by displacement interpolation, and analyzed the correctness of the boundary conditions. The APDL language is used to establish the parametric model of the sub-model. The central composite design is used to fit the response surface. Based on this, the MOGA method is used for optimization analysis, in order to find the best design with better structural strength and minimum quality. Combined with the requirements of production process and others, the fine design is engineered. Finally, the static strength test is completed to verify the rationality. The research results show that the optimized design of the car body meets the strength requirements; and the sub-model technology combined with multi-objective optimization is applied to the actual engineering to improve the analysis efficiency and make the optimization result more reasonable. Keywords: light railway vehicle, articulated carbody, sub-model technology, optimization

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