The exponential growth of information on the World Wide Web makes it increasingly difficult to discover relevant data about a specific topic. In this case, growing interest is emerging in focused crawler, a program that traverses the Internet by choosing relevant pages to a predefined topic and neglecting those out of concern. A new focused crawler based on Naive Bayes classifier was proposed here, which used an improved TF-IDF algorithm to extract the characteristics of page content and adopted Bayes classifier to compute the page rank. Then the crawler developed was compared with a BFS crawler and a PageRank crawler, and the results show that our crawler has better performance than the PageRank crawler and BFS crawler in harvest ratio.