In this paper, the CFD approach is used to simulate the thermal behavior in a sensitive high-Q gyroscope. The electromagnetically driving wires, in which the alternating current flows, are treated as Joule heat sources in the model. We found that the differences of the temperature, pressure and velocity along the driving direction and transversely across the proof masses increased as the gap height between the proof mass and top glass became smaller. Local pressure gradient is expected to possibly enhance the impact of any imperfect led by MEMS processes or designs on the offset of our tuning fork type gyroscope, which has been experimentally verified. A device with 200um gap gives a two-third offset down compared with that of its counterpart with 50um gap. Keywords- Offset, gyroscope, CFD, pressure gradient