From the view of design behavior，the merits of digital design system were analyzed，and then the evolution of digital design system was demonstrated.The related concepts about design behavior chain were established, and the computing method of design behavior quantity was proposed. Two digital design systems built by different product information modeling principles and software architecture technology were carried out to take behavior comparison experiment to complete the same product design task. Through quantitative analysis of the experimental data, the feasibility of discriminating the advantages and disadvantages of digital design system based on design behavioral experiments and important effect of such software system caused by different model principles and techniques were verified.