This paper reports a novel kind of solid micro-gyroscope, which is called piezoelectric micromachined modal gyroscope (PMMG). PMMG has large stiffness and robust resistance to shake and strike because there is no evident mass-spring component in its structure. This work focused on quantitative optimization of the gyroscope, which is still blank for such gyroscope. A set of quantitative indicators were developed to optimize the operation mode and corresponding device size was obtained. By FEM, the harmonic analysis was conducted to find the way to efficiently actuate the operation mode needed. At last, the Coriolis analysis was conducted to show the relation between angular velocity and differential output voltage by the Coriolis force under working condition.