Due to the continuous development of thermal gas mass flow meter is based on the principle of thermal diffusion, that is, the use of fluid flow through the heated object, the heated object of the heat dissipation of how much with the fluid flow rate into a certain proportional relationship. Specifically, the flow meter’s sensor has two standard and the RTD, has been used as a heat source, has been used to measure the fluid temperature, the fluid flows through, the heat loss of the heat source and the size of the flow into a non-linear relationship, the thermal gas mass flowmeter can be converted into a measurement of this relationship to measure the flow rate of the signal of the linear output.