By communicating with the host computer in the field through serial port, the parameters of CES cem emissions monitoring are collected, including flue gas velocity, temperature, pressure, smoke and dust, nitrogen oxides, sulfur dioxide, oxygen content and so on. Based on the data collected by K37A environmental data acquisition instrument, the converted values of smoke and dust, nitrogen oxides, sulfur dioxide and standard flow rate of flue gas are calculated by setting flue section area, local atmospheric pressure and excess air. Then the collected raw data and calculated parameters data are sent to the monitoring center through wireless mobile private network, so as to realize the real-time monitoring of enterprise on-site flue gas emissions. http://www.zetian-group.com/working-principle-of-flue-gas-cem-emissions-monitoring.html