This method is applicable to the determination of 11 ingredients in hair dye cosmetics using high-performance liquid chromatography. The 11 ingredients referred to in this method include Hydroxyethyl-4,5-diamino pyrazole sulfate, Hydroxyethyl-p-phenylenediamine sulfate, Tetraaminopyrimidine sulfate, 1,3-Bis-(2,4-diaminophenoxy)propane HCl, HC red No.3, Disperse black 9, Amino-6-chloro-4-nitrophenol, Basic red 76, Hydroxypropyl bis(N-hydroxyethyl-p-phenylenediamine) HCl, 2,6-Dimethoxy-3,5-pyridinediamine HCl, and 6-Methoxy-2-methylamino-3-aminopyridine 2HCl.