Taking the configuration design of the lifting device in a bridge crane as an example, this paper discusses the green optimal design method of enterprise's modular products with uncertain factors. The multi-layer generalized operators and comprehensive mathematical model under uncertainty are established based on the mapping relationship between product function and its structure. The model is transformed to an ascertaining combinatorial optimization model by de-fuzzy operator, and then it is solved by GA (Genetic Algorithm, GA). The method of chromosome encoding in binary that the chromosome is segmented by components and the genes in each segment are ranged as corresponding structures of each component, and the methods of selection and crossover and mutation operator are presented in this paper. The result of the green configuration design on the lifting device verifies the effectiveness and practical value of the method proposed in this paper.