For the 2 μm resolution lithography, in the lithography system with the digital micro-mirror device as space light modulator, we design a high resolution and large-area projection lens with new asymmetric structure assembly and fewer lens. By using ZEMAX optical design software to simulation-design and optimize, the results show that its optical path difference for entire field of view is less then λ/10, its distortion is less than 0.02％, its image space numerical aperture NA=0.158, its resolution is 2μm, its paraxial reduced ratio is β=-0.217. This can effectively reduce the DMD grid effect for the digital space mask and meet all kinds of requirement for projection lens optical system. Finally, we analyze the tolerance of the design results. By amending a few default tolerances and using the Monte Carlo method, it is verified the assembling and fabricating feasibility of this kind of new structure projection lens.