Abstract: To closely achieve diffraction-limited resolution, the surface shape of extreme ultraviolet (EUV) Schwarzschild objective requires about 1 nm (RMS value). But the mounting stress generated during the assembling process will affect the surface shape of optical components. Making quantitative calculation of mounting stress is a key point to obtain high-resolution images. On the basis of optical design and tolerance analysis, the influence of mounting stress on the surface shape of Schwarzschild objective is analyzed through the finite element model. The calculated results of the already designed structure show that, the surface shape error of primary mirror could reach to 0.7 nm (RMS value), but the influence on secondary could be ignored; the value of geometric optical transfer function (5000 lp/mm) decreased from 0.76 to 0.61 due to the surface shape error.