Web3D is a 3D graphics technology based on the Internet combined by network technology and virtual reality, apply it into the field of 3D product demo of Internet e-commerce is one of the currently development trends. This article will introduce the overview of Web3D's development and features of several domestic main Web3D technologies, analyze Web3D's application on aspect of product demo by KJ method, discuss the model of Web-based 3D interactive product demo used Flash 3D as an example, and provide technology and design ideas.