关键词: PageRank，主题漂移，偏重旧网页

Abstract: Pages ranking is one of the key technologies used in the design of a search engine. I}his paper described the famous PageRank algorithm. For the problems such as topic drift and emphasis on the old page, the approaches and features of a variety of improved algorithms were analysed in detail, hoping that can provide the basic support to the research in the future.

Key words: PageRank,Topic drift,Emphasis on the old page