The basic structure of a novel MEMS gyro based on bidirectional thermal expansion flow is proposed and its sensitive mechanism is revealed. The finite element method and CMOSOL are used to establish a three-dimensional model, and the temperature field of the bidirectional thermal expansion flow gyro sensitive element is calculated. The calculation results show that the bidirectional thermal expansion flow gyroscope exhibits gyroscopic effect, and the temperature sensitivity of the gyroscope is 1.577 K·（rad/s）-1, the sensitivity is 0.064 V·（rad/s）-1, and the nonlinearity is 6.855% when the input power is 70 mW and the input angular velocity ranges from -25-25 rad/s. The gyro is characterized by high sensitivity, low suppression cross-coupling and simple structure, and can be used in the fields of electronic equipment, aerospace and medical instruments etc.