In electron beam projection lithography (EPL), one of the most crucial tasks is to develop a data post-processing system, namely, a specific tool to expose a faithful pattern for every subfield on the wafer based on the pattern layout data. This system includes two basic flows. The 1st flow is common for reticle fabrication, and the 2nd flow is unique for EPL. During the 2nd flow, based on the LSI pattern data, electron optics space-charge effect correction will be automatically and rapidly executed and output to the EPL system in order to adjust parameters such as focus, magnification, rotation and astigmatism. In addition, this system should perform such tasks as segmentations of subfields (including complementary division), arrangement of stripes and reticlets, and alignment mark insertion. For proximity effect correction, we will first use a pattern shape modulation first. Shape modification at stitching boundaries is also investigated. In summary, to achieve conformable EPL delivery to customers, a new data post- processing system is developed in collaboration with some suppliers.