Aiming at the problem of poor design flexibility of customized product, a genetic algorithm based on genetic algorithm is proposed. The recombinant gene engineering is introduced in product design. The existing product design schemes are optimized by genetic algorithm, to meet with the diverse needs of customized products and realize the intelligent design. Taking the numerical control machine of a mechanical manufacturing enterprise as an example, the key technologies of genetic algorithm which are the fitness function, selection operator and crossover operator are designed, verifying the feasibility and effectiveness of the method.