Quantutative analysis of catechins by HPLC was studied. When the mobile phase was switched from the conventional(AOAC) Methanol, Acetonitril and Acetic acid solution in Hz0 to 0.06% Phosphate solution with Acetonitrile, N,N-Dimethyl formamide, and Ethyl acetate, retention time could be reduced from 45 min to 28 min, especially, we obtained sharper chromatogram of the compounds, either (-)EGCG or (-)ECG, which resulted in minimization of analytical erros. CVs of retention time (0.32∼3.97%) and peak area (1.61∼7.01%) indicated that the data were more reliable. Content of catechins in commerical teas analyzed by the method was 120.3∼153.7 ㎎/g in green teas which was about 4 times that in black tea.