In this paper, we revealed the sensitive mechanism of a MEMS z axis fluidic gyroscope based on the open airflow channel. The 3D transient finite element analysis method based on fluidstructure interaction was used to calculate the airflow field inside of the sensitive element and the numerical model is established. The calculation and test results indicated that: there was an open airflow channel inside of the sensitive element, and two inlets and one outlet were set up. The airflow was driven by the piezoelectric pump and entered from two inlets and was converged.The airflow from the nozzle created a jetsensitive body in the jetsensitive chamber and flew out of the outlet.At the static state, the jetsensitive bodywas symmetrically distributed relative to the hotwires r1 and r2, the speed gradient βx between the hotwires r1 and r2 as the two arms of bridgewas zero. Therefore, the bridge is balanced and output voltage is zero. When the angular velocity was applied, the jetsensitive body was deflected along zaxis under the action of the Coriolisforce; the jetsensitive body was no longer symmetrically distributed with respect to the hotwire r1 and r2, thus the velocity gradient βx between r1 and r2 increased with the increase of the angular velocity. Additionally, at the same condition of other materials and result parameters, the resistance value of two hotwires changed asymmetrically because of the asymmetric heat exchange between r1and r2 and sensitive jet flow.Therefore, the bridge was not balanced anymore and output an unbalanced voltage proportional to applied angular velocity. In the input range of ±120 (°)/s, the sensitivity of gyroscope was 2.0 μV/［(°)·s-1］, and simultaneously, the nonlinearity was better than 0.5%. In addition, the power consumption was 5.2 mW, the resistance value R of hotwire was 3 Ω and the temperature coefficient of resistance of hotwire was 2 600/℃.There was a directional flow between two inlets and outlet inside of the sensitive element of this open z-axis gyroscope based on MEMS, without circulation airflow. The sensitive element was simple in structure.