In this paper, a high-sensitivity thermal expansion gyro was proposed, and its sensitive mechanism was studied. A 2D model of the structure was created by COMSOL, and the finite element analysis was carried out. The results show that when the input power is 5 mW, the input angular velocity range is -1 000-1 000 (°)/s, the proposed thermal expansion gyroscope has gyroscopic effect and its temperature sensitivity is 2.12 mK·［(°)/s］-1. When the input power is 5 mW, the input angular velocity range is -1 000-1 000 (°)/s, the sensitivity of the proposed thermal expansion gyro is 1.98 mV·［(°)/s］-1, and the nonlinearity is 7.64%. The gyro sensitivity is improved compared to the previous structure. The high-sensitivity thermal expansion gyro has the advantages of strong impact resistance, low production cost, simple process and high reliability, and can be used in aerospace, consumer electronics, military and other fields.