This paper is concerned with the development of the web-based 3D monitoring system for the mobile robot via a standard protocol with user friendly human interface. Using the VRML (Virtual Reality Modeling Language), an operator can communicate with the mobile robot via a 3D-world model interface, compensate for the time delay problem of the Internet, and monitor the workflow of the robot. Virtual worlds for the environment are hand created before the operation of the robot system. But the information of specific interesting objects in the real world is updated to the virtual world by the image-processing of the mobile robot. The image-processing is performed by the coordinate relation of the world and the robot. And the appearance of new objects in the world is shown by mixture of 3D virtual scene and a real image. The employment of a standard protocol and human interface enables our monitoring system to be used by non-specialists from any Internet site, or by anyone from anywhere, without installing any specific software on the client side.