Abstract: The access of the users about a Web site represents the interest of users in the Web pages of the Web site.Each user s interest can be manifested by the sequence of each user access and access time in the Web.By analyzing the access path of Web user,similarity based on the sequence of each user access and access times can be put forward.Then,the concept of rough approximations is introduced in Leader cluster algorithm and the rough cluster algorithm based on Leader is suggested.Finally,the performance of th...