Hot wire type air-flow meter

The utility model relates to a hot wire type air-flow meter which comprises a wheatstone bridge provided with a bridge arm consisting of a temperature resistor Rn and other three bridge arms consisting of other three precision resistors R1, R2 and R3 as well as an operational amplifier U2A; an output end of the operational amplifier U2A is connected on the base electrode of a triode Q1, one bridge arm of the wheatstone bridge is connected at an inverting input end of an operational amplifier U2B, a reference voltage V1 is connected at a non-inverting input end of the operational amplifier U2B, a monolithic processor controlling unit U1 is also arranged at an input end of the operational amplifier U2B, a temperature sensor RH is connected on the monolithic processor controlling unit U1, and the monolithic processor controlling unit U1 transforms a temperature signal detected through the temperature sensor RH into a voltage signal and performs comparison to the voltage signal and the reference voltage V1, and t