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A measure, control, remote transmission and management system of CNG flow based on Modbus RTU protocol and non-contact IC card is proposed. The system with the main control chip STC89C516 can implement CNG flow collection, data remote transmission, history record query, parameter settings, real-time display, sound and light alarm. The Coriolis mass flow-meter and host computer serially communicate with the microcontroller based on Modbus RTU protocol by RS485 interface. The non-contact IC card is used to modify the system parameter and balance with the help of the password entered by the keyboard. The strict password protection system is adopted to ensure the data safety in the IC card. The test results demonstrate that the system smoothly runs, accurately acquire data, remotely transfer data and display. It has the advantages of simple operation, high detection accuracy, strong anti-interference ability and low circuit cost, and has broad application prospects.