Because of the development of using new technologies like computer science in mathematics education, it is important for us to rethink about one of the critical terms for teacher’s practice in classroom: teacher knowledge. There are many researches pay attention to definite what is teacher knowledge or what kind of knowledge teacher needs. As some researchers said we need to take technologies into account if we want to describe teacher knowledge. Teacher knowledge can be reflected in their class behavior. So this research aims at analyzing teacher’s didactical practice with one of the important technologies: dynamic geometry software. Taking instrumental orchestration as critical theoretical framework, this study describes teacher’s activities with dynamic geometry software in the classroom based on the view of their knowledge. It chose 5 Chinese teachers and 1 French teacher to observe their mathematics lessons in order to analyze their knowledge shown in their practice with technology. The main question of this research is as following:1.1What can we learn about the teachers’ knowledge shown in their instrumental orchestration by contrasting the different usage of DGS between Chinese and French teachers? 1.1.1What can we learn from analyzing the roles of DGS in mathematics tasks? 2.1.2What can we learn from tasks organization by contrasting the teaching practice between Chinese and French teachers?3.1.3What can we learn the teacher-student interaction by contrasting French and Chinese teachers?In order to answer these questions, I focus on the roles of dynamic geometry software in mathematics tasks and the questions or feedbacks in the teacher-student interaction. Dynamic geometry software plays two main roles in mathematics teaching and learning: amplifier and generator. This kind of software also affects teacher-student interaction. Teacher would show their different focus by using software for example only focus on mathematics or focus on mathematics related to software. As designed, this research chooses several mathematics teachers from two different contexts to contrast their knowledge which reflected into teaching practice in the situation created by technologies. I altogether observed and recorded 11 lessons for them. They would also be interviewed before and after their mathematics lessons which would be recorded by the author, to make deep understanding of their opinions on DGS.Based on the analysis, different teachers show their different views on the roles of dynamic geometry software. Most of them see software as an amplifier of presenting contents during the teaching process, although the software can change learners’ strategy to solve the tasks. And during the interaction, most teachers focus on mathematics contents without any technology, although they choose different ways to orchestrate lessons. There are many factors which may affect teachers’ using of software, like physical configuration, ability of students, teaching objective, examination, which talked by teachers during the interview and also need to much further studies for researchers.