This gas meter is an intelligent prepaid flow metering instrument that uses NB IoT communication technology. It is a low-cost, high reliability, and high security wide area Internet of Things technology that integrates and evolves with current cellular networks. Supporting the three major mainstream operators, with low failure rates and maintenance costs, and a high success rate in meter reading. Suitable for flow accumulation measurement of combustible gases such as natural gas, liquefied gas, biogas, and urban pipeline gas with a pressure range of (0.5~50) kPa, and can achieve prepaid management. It can be widely used in urban households.