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With the development of optimal technology, optimal design of structure has been applied in the vehicle field. On the base of finite element method analysis on bus frame structure, a non-linear mapping function from multiple input data (design variables) to multiple output data (displacement, stresses and frequency calculated by FEM) was constructed within BP neural networks. It is necessary to obtain the objective function values in optimum design of structures by using genetic algorithms. Optimal design of structures was put forward by using genetic algorithms. The results showed that on the basis of ANN and GE, optimal technology applied in optimal design of bus structure was effective and reasonable.