The analytical method for roller pen inks was established by capillary zone electrophoresis.After optimizing such conditions as20mmol桙L borate buffer at pH 8.5, 100μm×40cm fused silica capillary column,separation voltage of15kV,photo diode array (PDA) detector and scanning range190~600nm were adopted in experiment.Electropherogram of different roller pen inks' extracts were obtained. The problem of relative writing age was investigated from relative changes between different dyes in inks detected by PDA in visible wavelength.