Abstract: Virtual prototype reality design (VPRD) is a new technique that has developed recently. Here studied are the problem of product modeling as well as the problem of integration product and process design based on virtual environment simulation. The inference machine model for function-structure project is one of important modules which consist of the framework of VRPD. According to the complexity of function-module combination on project optimization issue, the realizing techniques on building the inference machine model for function-structure project based on genetic algorithm(GA) are given. The algorithms of double-stranded exclusive OR crossover operator and adaptive communication selection to crossover operation are proposed. The advantage of GA-model is verified by the empirical test of instruments. The presented techniques have been applied to a decision support system (DSS) for the new product development of instruments.