With the development of Web application,virtual reality technology based on Web is popular.In Web3D field,the old standard of VRML(Virtual Reality Modeling Language)has many problems and is not fit for the development.So the Web3D Consortium provides a next generation standard for Web3DX3D(Extensible 3D specification).X3D,using multiple file encodings describing the same abstract model including XML,has a modular architecture allowing a range of levels of adoption and support for many different market types.It also has a unified application programming model and an expanded specification structure.The technology character of X3D is mainly analyzed.Also the background,development and supporting tools of X3D are introduced.And then an example of application using X3D is given.