Abstract: The paper aims to establish the method to determine the monosaccharide composition and monosaccharide ratio in propylene glycol alginate sodium sulphate (PSS). Samples were hydrolyzed with trifluoroacetic acid, neutralized with sodium hydroxide solution after the reaction conditions for sample pretreatment were optimized via orthogonal analysis. A high performance anion exchange chromatograghy (HPAEC) coupled with pulsed amperometric detector (PAD) was performed on a CarboPac^®PA20, using 200 mmol·L^-1 sodium hydroxide solution and 1 mol·L^-1 sodium acetate solution as mobile phase. The established HPAEC-PAD method was validated by testing the linear relationship, precision and accuracy, and showed exclusive, sensitive, rapid and wide use. The monosaccharide composition of PSS from different manufacture can be accurately determined with great significance for the structural identification of PSS.