Based on the partial differential equation related to the displacement of bimorph deformable mirror with free boundary condition and its applied voltage deduced by S. A. Kokorowski, a matrix of static response functions f(r, θ) of mirror is derived with Gaussian iteration. Considering the statistical weight factors of different Zernike model aberrations caused by atmospheric turbulence, and the different arrangements of mirror positioning, the optimization of the bimorph deformable mirror is analyzed. The results indicate that, the correction capability of bimorph deformable mirror is greatly dependent on the statistic weight function of the corrected Zernike model wave aberrations induced by atmospheric air turbulence, so far as to the optimization design of mirror. And the different ways of mirror positioning will slightly affect its correction capability.