EGCG (Epigallocatechin Gallate), one of the catechin compounds abundant mainly in green tea, has chemopreventive effects against carcinogenesis. The extract at 50 ℃ water from the powder of green tea was partitioned with chloroform and ethyl acetate. The resulting solution was further purified on three different columns, 4.6x250 mm (40/63 μm), 4.6x250 mm (15 μm), 3.9x300 mm (10 μm), in order to separate EGCG among catechin compounds from green tea. In a given packing size, the composition of the binary mobile phase, water and acetonitrile, with 0.1% acetic acid was changed to operate in optimized experimental conditions. In a packed column of 40/63 μm packing, catechin compounds were not well separated. With packing sizes of 15 and 10 μm, the resolution of EGCG among catechin compounds was better, and maximum injection volume to separate EGCG purely was 100 and 480 μl, respectively. The study on the effect of packing size may be utilized for preparative chromatographic separation.