A MEMS gyro based on the principle of bi-directional thermal expansion flow is proposed and validated. The gyro generates airflow through the instantaneous temperature change of the heater, which induces a corresponding temperature change in a thermistor. This temperature variation is then converted into an output voltage, enabling accurate detection of angular velocity along the Z-axis. In order to further improve the performance of the gyroscope, reduce the cross-coupling, and optimize the preparation process, structural design optimization is necessary. COMSOL Multiphysics simulation software is used to explore the influence of factors such as the positional distribution of the sensitive components, the placement mode, and the uni-directional and bi-directional thermal expansion flows on the sensitivity. Through systematic simulation analysis, the optimal placement range of sensitive elements is clarified, with the parallel placement determined to be determined to be the most effective configuration. Furthermore, both theoretical and simulation results demonstrate that the bidirectional thermal expansion flow realizes higher output sensitivity and superior cross-coupling suppression compared to its uni-directional counterpart. Finally, based on the above findings, a MEMS gyro is prepared and its performance is experimentally evaluated. The test results show that the gyro is capable of detecting the angular rate in the range of ±600°/s with a sensitivity of 3.04 mV/（°·s-1） and a nonlinearity of 7.09%, under a heater drive signal of 2.5 V, 50% duty cycle, and 10 Hz square wave. The experimental results are consistent with the numerical simulations, confirming that the gyro offers high sensitivity, effective cross-coupling suppression, and a simplified fabrication process. These characteristics make it suitable for applications electronic devices, aerospace and medical instruments.