One of the focuses on the current Chinese mathematics curriculum reform is shifting from “teaching with textbook” to “using the textbook for teaching”. Based on this background, this study aims to analyse the use of mathematics textbooks by an excellent Junior High School mathematics teacher in mathematics classroom. The content analysis method is used to compare the textbooks and the teaching materials actually used by teachers from teaching content and design sequence. In terms of teaching content, teachers have a higher degree of recognition of the mathematics textbooks contents and use most contents in the textbooks. However, the content of the textbook will be split, reorganized, supplemented and deleted when used. Moreover, teachers adjusted the order of teaching based on textbooks. It can be seen that teachers have redesigned textbooks when using them. This research helps inform that teachers should not use math textbooks directly, but should modify them according to their respective schools.