This paper, we discuss the principle of cluster analysis and develop the Web-based software based on Java applet. The system is accomplished based on object-oriented technique. The system can be embedded into Web page and display via browsers. The applet can perform two basic operations from the button of demo and the button of cluster analysis on interface. One operation from demo can completely demonstrate cluster procedure, and the other operation from cluster analysis can obtain the classifications of samples according to the data inputted by user. Three cluster methods including single linkage, complete and faster cluster are used to demo and cluster analysis, and the hierarchical cluster graph can plot and display at the same time. For the sake of convenience, the applet provides the pop windows that allow users to input and edit data.