Objective: Study on a specific and sensitive determination method of the total organic acid. Method: It has been developed the method that by citric acid as index based on the formation of hydroximic acid from the organic acid in the presence of dlcyclohexylcarbodiimide (DCC) and hydroxylamine perchlorate (HAP) as well as the formation of purple ferric hydroxamate from hydroximic acid in the presence of acidic ferric perchlorate solution in Pinellia pedatisecta. Result: A determination method has established by optimization of conditions. Through the study methodology

approach was consistent with requirements determination:citric acid has a good linear relationship between the concentrations and the absorbance of schaftoside in the ranges of 0.078-0.390 g·L-1(r=0.999 8)

and the average recovery was 99.91% (RSD 1.32%

n=9). Conclusion: The performance of the method was convenient

sensitive and has a good reproducibility

and can be used to determination of the organic acids in Chinese medicine.