In order to keep a good surface-profile in many different conditions,active correction is carried out to correct the surface-profile error of the large-aperture standard planar mirror. The support system consists of an active correction system and a passive support system. The mirror is balanced by a passive support system combining axial support and lateral support. When mirror's conditions changes,the active corrective forces are calculated by establishing stiffness matrix by Zerniker Polynomials and using the least square method. Then surface-profile of the mirror will be corrected by loading the active corrective forces on axial support. Regardless of the production error of the mirror and consider the influence by gravity,The simulation results show that When the mirror working in 45°,the surface-profile error can be corrected from the initial RMS=λ/8 (λ=632.8 nm)to λ/74.When it works horizontally,the surface-profile error can be corrected from the initial RMS=λ/6 to λ/70.The simulation results show that the active support method can keep a good surface-profile of large-aperture standard planar mirror in different conditions. It provides a basis that large-aperture standard planar mirror can maintain good surface-profile in many working conditions.