Deformable mirror as the key part of the adaptive optics systems, plays a role of correcting the wavefront error. The transversal piezoelectric deformable mirror is widely used, and its design parameters have important influence on the system performance, so the optimization is needed. The simulation results show that minishing the thickness of Si mirror and PZT player can increase the maximal displacement, but decrease the first natural frequency of the system. The system working requirements can be satisfied by the orthogonal matching of thicknesses. The material and structure parameters of the fixture affect the system thermal deformation performance. Using the same material as the mirror for the fixture, the system thermal deformation is minimum, the height and wall thickness of the fixture can be optimized to reduce or even eliminate the system thermal deformation. Finally, the influence function of the discrete electrode is obtained by the simulation of voltage performance.