This paper investigates the problem of information crawling in Web site in penetration testing. In order to meet the requirement of high efficiency and comprehensiveness of information fetching in Web penetration test, in this paper, we researched and analyzed the Web site, and proposed a web crawler strategy based on navigation link. Besides, to optimize the efficiency of URL de-emphasis, we improved the traditional MD5 de-emphasis algorithm by reducing the number of iterations. The experimental results show that the coverage of information fetching and web page download efficiency are raised with the Strategy of Web crawler.