At present, intelligent water meters manufactured in China can be divided into two categories: prepaid water meters and remote water meters. Their common feature is that the sensors for measuring water flow still use ordinary water meters. By installing sensor elements at a certain position of the dial pointer or gear group of water meters, the mechanical reading of raw water meters is converted into electrical signal data, and then entered. Collection, transmission and storage are carried out automatically or manually according to the requirements of settlement and transaction mode. Because their basic meters are all speed meters, they are also classified as speed meters according to the principle of water meters. They have only improved the reading mode and indicator mechanism, and added the functions of automatic meter reading system such as prepayment and remote reading, while the measuring mechanism, transmission mode or machine. The accuracy (accuracy) level of mechanical water meter is 2.0 level as that of ordinary mechanical water meter.