Abstract: To evaluate corrective capability and thus obtaining the maximum capability is a key point in the design and development of active mirrors. The closest profile of an active mirror to a given Zernike element profile can be obtained through linear combination of actuator influence functions, as measured by experiment or calculated by finite element method (FEM). The consistent level of the Zernike element profile with the actuator array generated profile can be regarded as an index of capability of an active mirror. Static analysis via FEM is studied, and the optimum scheme of actuator array for an active mirror with maximum corrective capability is achieved.