An over-sized monolithic holographic lens with a micron plane precision of 0.4 μm is fabricated on a quartz substrate well polished by Micro-electro-mechanical system(MEMs) process. Some improved methods are used in this series process, such as the stepper projection exposure with a resolution of 0.2 μm and the stitching method, the improved ICP ( Inductively Coupled Plasma)dry etching technology for a quartz, the physical cleaning method designed especially and a lot of other supporting processes. The ideal surface shape curve of cross section for the hologram lens is a piecewise parabola. A single lens is horizontally arrayed by 23 column cell structures with a width about 2.966 mm. Because of the difficulty in practice, the 4-step structure with an equal depth and an unequal width is used to fit it. At last, single piece square hologram lenses with the area more than 68 mm×68 mm are obtained at a 4 in(10.16 cm)circle piece. The step profiler, scanning electron microscope, high-powered and resolution optical microscope are used to measure lens accuracy at different stages. The results indicate that the lens has a plane precision of 0.4 μm, vertical precision of 30 nm, and shows a good vertical wall shape and etching uniformity. This process technology can be used for small batch production, and the cost is moderate. It is suitable for processing the same grade lenses with the size of 6 in(15.24 cm), and also for processing the sapphire substrates.