In order to study the capability of fitting Zernike polynomial aberration of the deformation mirror, two finite element models for deformation mirrors in different arrangements are established. Analysis is proceeded by giving theoretic displacements to actuators. The result indicates that the relationship between the different actuator arrangements and capability of fitting aberration, and shows that the arrangement of 57 actuators can fit the aberration to λ/20 or smaller and the print-through effects of actuators acted on the deformation mirror are verified.