​Solar energy is a huge energy that people can use in nature. The growth of all life on Earth is related to solar radiation. In recent years, many countries are exploring effective ways to use solar energy. With more and more solar water heaters being invented and widely used, the performance of residential solar water heaters has attracted more and more attention. This paper briefly analyses the advantages of residential solar water heater compared with other water heaters, and the heat transfer efficiency between residential solar water heater and the sun, atmosphere and environment.