A new resonant micro-sensor modeled on trichoid sensillum of insects which can detect low-velocity gas flow is proposed and fabricated for the first time. The relationship between Reynolds number and drag coefficient which helps determine resistance when gas passes around infinite long beam is obtained numerically and the effect of size choice of infinite long beam on this relationship is put forward. Based on this relationship, theoretical model of this micro-sensor is deduced in which the relationship between the velocity of gas flow and the frequency shift of the resonator is obtained and the linear region of this micro-sensor is found. FEA (finite element analysis) is conducted which asserts that when gas ranges in low Reynolds number, typically when Reynolds number is less than one, there exists excellent linear relationship between input and output of this micro-sensor. What is more, the prototype of this micro-sensor is successfully fabricated.