Immersive virtual reality system and unimmersive virtual reality system are two different virtual reality systems.Web 3D is a virtual reality system for web but not a immersive one, which can be realized by VRML(Virtual Reality Modeling Language), XML(eXtensible Markup Language),JAVA, animation script language,stream media technology. These technologies and standards are studied and reviewed . Then a product simulation system based on Web 3D is developed. The system reads data from CAD(computer aided design) system first, and then it converts these data into data which agree with Web 3D standards. Finally, the data are converted into data which can be released in internet. This system is very useful for products real-time demonstrating in internet and electronical emmerce.