As a new design pattern, virtual optimization design is a multiple subjects crossed synthetically technique and will become the trend of modern mechanical products design. It can avoid the repeated from design to trial-manufacture and test. The designers can analyze and optimize the product structures in virtual visualization environment. The design cycle shortened and the cost reduced. The paper analyzed the peculiarity of virtual optimization design, and put forwards the thought and flow to fulfill virtual optimization design. Finally, the tail bracket of the NC lathe as an example to optimize is studied