The big dimension telescope main mirror was exactly analyzed by ABAQUS finite element software using none linearity analysis method, which can quantitatively analyze the main mirror distortion caused by the big dimension telescope main mirror self weight. The scrub form of punish function was introduced to the scrub contact of the main mirror groupware in the analysis course. The ball head touch and core axes touch were molded and an emergency analysis of the mirror groupware Y and Z directions were completed. The surface appearance change was very little, which was caused by the self weight of the mirror groupware. The Y and Z directions of the RMS were 16 nm and 13 nm. And the Yand Z directions of the main mirror rolling the X direction were 0.5″ and 0.02″. The system can completely satisfies the using condition. The analysis can offer some reference to the adding research of the telescope.