The optical elements with the thickness and length or diameter ratio less than 1:10, or sometime 1:40, are called thin optical elements. So the processing difficulty of the thin optical elements is aperture deformation, and high precision surface processing requirements make the processing work more difficult. The aperture deformation reasons in processing main include cementation deformation, thermal deformation and stress deformation. So the difficulty of thin optical elements processing is how to eliminate or reduce the deformations to get the needed high precision thin elements. The reasons and solutions of the above three kinds of deformation are introduced to provide a certain guidance to the actual production.