Based on optical design theory of imaging illumination and non-imaging optical theory, an initial optical structure of illumination system is established according to the special requirements of Talbot self-imaging lithographic equipment. The optical design software Zemax is applied to optimize the initial structure. The software Lighttools is used to set up models and perform large-scale ray tracing. The simulation result shows that the nonuniformity of illumination approaches 1.83% in the illumination area of 60 mm×60 mm. Meanwhile, the power density is no less than 1.15 mW·mm-2. The tolerance analysis is carried out on the illumination system. The results show that the illumination system satisfies the demand of Talbot self-imaging lithography.