The writing styles of TIME and Newsweek are analyzed using a specially developed linguistic program. These two news magazines were chosen because of their wide popularity. As for the results, it became obvious that both the frequency curve of words and that of characters have not changed for the past 60 years. Also, we have found that the frequency curves have some inflection points and that the genre of English writings can be identified by these points. After counting the percentage of required vocabulary for junior high school students and high school students in English writings, we can derive the relative difficulties of them using fuzzy reasoning. Fuzzy rules are constructed using features of the characteristic curves. We feel it would be a good guide index when selecting textbooks or supplementary readers.