The task of clustering Web sessions is to group Web sessions based on similarity and consists of maximizing the intra-
group similarity while minimizing the inter-group similarity．
The first and foremost question needed to be considered in clustering
W b sessions is how to measure the similarity between Web
sessions．However．there are many shortcomings in traditiona1
measurements．This paper introduces a new method for measuring
similarities between Web pages that takes into account not only the
URL but also the viewing time of the visited web page．Yhen we
give a new method to measure the similarity of Web sessions using
sequence alignment and the similarity of W eb page access in detail
Experiments have proved that our method is valid and e幣cient．
