Abstract: The boundary structural parameters of a silicon resonant pressure microsensor are optimized in this paper. The preliminary sensing unit of the above sensor is a square silicon diaphragm, which senses the measured pressure directly. And the final sensing unit of the above sensor is a silicon beam resonator, which is attached on the upper surface of the above diaphragm. The above silicon beam senses the measured pressure indirectly. Based on reducing the boundary structural disturbances of the sensing structure for the above microsensor and increasing the Q factor of the beam resonator, the boundary structural parameters of the sensing structure are optimized by using the finite element method.