A mind map is a diagram in which information is arranged visually and sequentially. Therefore, the use of mind maps in teaching has been used by many educators around the world; they showed that it much supports the teaching process of teachers and students' learning process. Also, with the mind map approach in teaching mathematics, we conducted experimental teaching in teaching the topics of straight line and circle equations - Geometry 10 in high school mathematics program in Vietnam. By using mind maps in reviewing knowledge, in teaching new knowledge and in systematizing knowledge for two experimental classes, we found that the learning results of students in the two experimental classes were actually higher than those of the two control classes. From our experience gained through experimental teaching, we believe that teaching mathematics with the help of mind maps will be a teaching method that contributes to improving the effectiveness of mathematics education in schools