It has been shown that myopia is a hereditary eye disease. The majority of adolescents with myopia or simple myopia below 600 diopters are polygenic. The onset of myopia is 60% determined by genetic factors and 40% by acquired environmental factors. High myopia of more than 600 degrees is chromosomally recessive, and its onset is entirely determined by genetic factors, with little or no role for acquired environmental factors. Under the premise that genetic factors cannot be changed, the prevention of low and moderate myopia mainly focuses on acquired environmental factors. Environmental factors are quite important in the development of low and moderate myopia. Children and adolescents whose eyes are not yet well developed can develop myopia due to changes in refraction and anterior and posterior diameters of the eyes when they are subjected to prolonged and stressful close-distance use of the eyes as well as poor visual hygiene, e.g. overloading of homework of students, prolonged close-distance use of the eyes, and prolonged and uncontrolled playing of video games and watching of television. The prevention and treatment of myopia in adolescents should not only start from changing the acquired environmental factors and reducing the burden of schoolwork on students, but more importantly, parents should have the concept of early prevention, which is more effective before it happens. That is to say, when the child does not have any myopia manifestation, give the child a refractive screening, 6 months above the baby can do simple and quick non-contact painless preliminary refractive examination, so that according to the child’s refractive status to receive eye guidance. It is too late to prevent vision loss. In addition, the preschool children also need to pay attention to the following health care measures: 1, cultivate good visual hygiene habits, learning to write, remember the three “one”: hold the pen from the pen tip of the hand an inch (3.3 cm), chest from the table a fist (6 ~ 7 cm), books from the eyes of the feet (33 cm), to maintain proper reading and writing posture, do not walk, ride or lie down in the car. Walking, riding in the car or lying down when reading, in order to reduce visual fatigue. 2. Increase the lighting in the classroom to ensure adequate lighting from the left front. The appropriate illumination for reading and writing is 100 to 200 Lux (lux), equivalent to 40 watts of incandescent lamps or 8 watts of fluorescent lamps, too strong or too weak lighting can cause excessive enhancement of eye adjustment. 3, textbooks and reading paper and printing should be high quality, paper should be white, ink should be black, increase the contrast between black and white, should not read yellow paper, printing unclear books and magazines. 4, the duration of continuous reading and writing should not be too long, every hour of reading and writing should look away or rest for 10 minutes, and advocate adherence to eye exercises, as much as possible to outdoor activities. 5. Regularly check your eyesight and refractive error so that you can detect myopia early and get timely treatment. 6. Some studies show that myopia is related to dietary preferences, such as eating sweets, starch, smoked protein foods and excessive consumption of monosodium glutamate (MSG). Should eat more fresh vegetables, citrus fruits and nourish the liver and spleen, beneficial to the blood type of food, such as aquatic products, carrots, tomatoes, purple cabbage, taro, sweet potatoes, walnuts, peanuts, black sesame, milk soy milk and soy products. In fact, if food can effectively prevent and control myopia is too simple, in fact, not picky, eat everything is not only for the eyes, but also for the development of children and adolescents body is very important.