In the production and life of human beings, water resources are essential substances. Nowadays, environmental issues have received much attention. People are particularly concerned about water quality safety issues. The safety and quality of domestic water has also received wide attention from all walks of life. In order to make people more intuitive and easy to know the water quality status of domestic water, this study provides a household water quality detection system based on narrow band Internet of Things technology, and gives the overall design scheme, hardware design, software design, and test results of the system. This system can detect the pH value, temperature value, and Total Dissolved Solids (TDS value) of household water in real time, and synchronize to the cloud platform through NB-IoT communication technology in real time. The system has clear functions, simple operation, and easy observation. It has a good user experience and commercial application value.