Objective:To improve the determination method of sodium alginate pharmaceutical excipient in the USP for the analysis of sodium alginate content in the Chinese market.Methods:High and low viscosity sodium alginate samples were subject to acid-water and acid-isopropanol precipitation methods,respectively,followed by acid-base neutralization capacity analysis to calculate the sodium alginate content in the sample.Results:The line-ar relations were good between sample weight and the volume of sodium hydroxide titrant consumed in the range of 0.5-1.5g(R2=1.000 0,0.999 9).For two precipitation methods,the average recovery rates were 104.2%with RSD value of 0.3%(n=6)and 101.9%with RSD value of 0.2%(n=6),respectively.Conclusion:The improved method has good specificity,accuracy and precision,which is convenient and low cost that can be performed in the assay of sodium alginate pharmaceutical excipient.