In mathematics teaching, classroom practice is an important link in the teaching process, which can check students' mastery of knowledge in time and is also a reference for teachers to feedback the teaching effect. Appropriate classroom practice is not only a process of strengthening students' knowledge memory, but also a process of deepening knowledge understanding and application. It is also an important part of modern efficient classroom and a demonstration of teachers' comprehensive teaching ability. How to effectively design classroom exercises, combined with teaching practice and learning experience, has the following experiences: First, exercise design should be clear in purpose and expression. Exercise design must be designed around the teaching focus and teaching objectives of each class, which is closely related to the teaching of each class and cannot involve too many irrelevant knowledge points, that is, the purpose of design should be clear, the expression should be precise, targeted and the difficulty should be moderate. Teachers should consider what exercises to design, why to design them in this way, whether to stimulate students' interest or to complete teaching tasks; Whether to pay attention to the cognitive goal, emotional goal or ability goal of teaching. A good exercise design must be clear, accurate and rigorous. Combined with teaching experience, I realized that when teaching important knowledge points in primary school mathematics teaching, the purpose of exercise design must be clear, and a large number of disorderly exercises may not achieve the expected results. When teaching simple arithmetic in grade four, I simply think that a lot of practice will make students learn to use simple arithmetic quickly.