Product reviews are not only useful for trade companies to improve the quality of products, but also helpful for customers to purchase products reasonably, thus product reviews mining is valuable in application and research. In this paper, we devote the research on book reviews. We first propose a polarity dictionary construction method based on the improved CHI, and realizes dynamic addition of the dictionary; Second, the polarity calculation formula of the transitional complex sentences is improved to be applicable to book reviews. Considering that some book reviews have titles and these titles generally express the reviewers’ opinion tendency, so we further propose an opinion polarity analysis method based on the titles and the improved polarity calculation formula of the heavy transitional sentences. The experimental results show that the approach proposed in this paper is effective.