Children should not swim more than 2 hours, the specific time can be based on the child’s physical strength, fitness, etc., to avoid too long. If it is the first time to learn to swim or usually no exercise habits of children, should avoid a one-time too long or too intense exercise, each practice swimming time of about 1 hour can be. If it is often swimming exercise children, the duration should generally not exceed 1.5-2 hours. The day before swimming children should ensure sufficient sleep, 1-2 hours before swimming should be supplemented with carbohydrates, and half an hour after swimming should also be supplemented with protein in time to enhance physical strength. In addition, parents need to remind children that they should pay attention to adequate preparatory activities before swimming; they need to protect their eyes during swimming and avoid holding their breath for a long time; they should wear good clothes in time after swimming to prevent catching a cold.