To meet the research requirements of 45 nm node or even below microlithography, the configurations and specifications of experimental lens are determined. Based on the aberration theory, several refractive elements are inserted into a non-concentric all-reflective Schwarzschild system with a small central obstruction so as to achieve smaller obstruction and hyper-numerical aperture. A Schwarzschild catadioptric lithographic lens whose numerical aperture is 1.20 is designed with a small central obstruction. Designing results show that the objective′s working bandwidth is 100 pm, viewing field of image is 50 \mm, the linear obstruction ratio is 13%, modulation transfer function is greater than 0.45 at the resolution of 80 nm (6240 lp/mm), and its distortions of all field points are below 6.5 nm. It can meet the requirement of deep ultraviolet immersion lithographic experiment with 45 nm nodes.