Abstract: The promotion of urbanization has led to an increasing energy consumption,and energy conservation and environmental protection are receiving more and more attention. The requirements for water supply and drainage system of residential buildings have been further improved. In the water supply and drainage system,the hot water system plays a crucial role,but it is also a part of the high energy consumption in residential buildings. Therefore,the reasonable selection of hot water preparation methods is of great significance. Solar energy belongs to clean and renewable energy,which is easy to collect,can be directly developed and utilized,and has great potential for utilization. It is an important energy source to replace traditional energy and reduce urban and rural carbon emissions. This paper taking a residential project in Wuhan City as an example to apply solar hot water systems in the water supply and drainage system of residential buildings. From three aspects:solar hot water system setting,carbon emission calculation,and economic benefits,value of corresponding design parameters for the solar hot water system and the economic benefits of actual operation are analyzed.The research results show that solar hot water systems can to some extent meet the domestic hot water needs of users in the residential buildings. Solar hot water systems can save economic costs and have significant energy conservation effects.