Abstract: Web structure optimization technique plays a significant role in reducing latency and improving the access efficiency. This paper presents the Web Hierarchy Model (WHM) which is constructed based on user access path. Then the Web Conceptual Mode (WCM) is obtained by clustering pages in the same hierarchy according to the pages' similarity. According to the experiments and analyzes, WCM can show the structure of Web clearly under moderately clustering. Furthermore the model is implemented in web prefetching system, in the aspect of prefetching efficiency, the clustering algorithm used in this model is superior to the traditional method and it is feasible and efficient.