Using an actuator array to thrust load onto the back of a mirror can control the profile of the mirror or correct its residual irregularity. It is meaningful to study how to improve the control or correction capability of active mirror for practice. The closest profile of a mirror to a given Zernike element profile can be obtained through linear combination of the influence functions. The algorithm of evaluating an active mirror's capability of correction is presented. Static analysis via Finite Element Method (FEM) is studied at various conditions with different amount and distribution of actuators, as well as the fixing manner, and the optimum scheme of actuator array is yielded.