Abstract: RP-HPLC with DAD was applied to the identification of components of blue ink of ball pens.The Xterra MS C18 column (3.9 mm×150 mm,5 μm) was used as stationary phase,and a mixed solution of 0.01 mol·L-1 NH4HCO3 solution and acetonitrile mixed in the ratio of 35 to 65 by volume was used as mobile phase with a flow rate of 0.8 mL·min-1.A total of 88 kinds of blue ink of different categories were taken as testing samples,and based on their different components,including crystal violet,methyl violet,tetramethyl pararosaniline,victoria blue B,victoria blue BO,sulfonated copper phthalocyanine,rhodamine B,the ink samples were divided into 9 groups.The identification of brands of among these groups was proposed based on relative peak area of the components of ink.