Extracting log template is a very effective way to handle massive system logs. In this study, the Web system log is used as the entry point, extracts the log template by using signature tree model. Based on it, we studied and improved the log preprocessing and template expression generation methods. Aiming at the complex structure problem of syslog, the preprocessing method based on text similarity is adopted to realize the classification of log messages. We used the max template matching method to solve the low template matching problem caused by the inconsistent log format and word-cutting. Finally, we evaluate the experiment of this log template extraction method. The results show that the accuracy of the method is 96.4%, and the template matching degree is greatly increased.