Abstract: GaN is a strong candidate for making MEMS resonators because of its higher acoustic velocity compared with silicon and higher piezoelectric coefficient compared with aluminum nitride (AlN). A silicon-based piezoelectric GaN MEMS resonator was designed. The two-dimensional electron gas (2DEG) in GaN can be used as a switch embedded electrode characteristic, and a thin-film micromechanical resonator composed of electrodes, piezoelectric films, and electrodes can be realized through GaN piezoelectric materials. During operation, a thickness shear vibration mode is generated in the piezoelectric film between the two electrodes, and oscillation is formed inside the piezoelectric film. The orthogonal stress (σx and σy) of the piezoelectric effect can provide the relevant stress field to increase Electromechanical resonance. The resonator is fabricated by MEMS technology and planar processing technology. The physical size of GaN resonant unit is 90 μm². The GaN resonator is formatted by releasing silicon substrate (111) using the XeF2 gas, which does not damage the resonator without loading power. In this way, the roughness and residual stress of the resonator thin can be reduced, and the scattering caused by impurities and defects can be avoided. The test results show that the resonant frequency is 12.56 MHz and the quality factor of the resonant cavity is 3 600.