To manufacture the integrated circuit chips at 90 nm or below their nodes by using a 193 nm exposed wavelength deep ultraviolet lithography, a beam shaping unit for the lithographic illumination system was designed to achieve the annular illumination and the continuous adjustment of a partial coherent factor σ to meet the requirements of different exposed line widths. Firstly, the function relationships between the moving distance of axicon and the light beam magnification were deduced by using the laws of geometric optics and trigonometric functions, and the ranges of parameters of axicon were determined after analyzing the feasibility of zoom cam and the tolerance sensitivities. Then, the axicon and zoom lens were combined to implement the beam shaping unit. Finally, a kind of reducing scale zoom lens was designed to add into the combined system to achieve the continuously adjustment of the σ. The result shows that the normalized annular width Δσ and the outer diameter of annulus σouter can be adjusted continuously in the range of ［0.25, 1］ and ［0.4, 1］, respectively , which meets the needs of design.