[Objective] To discuss the detection method for SO2 residual in FLOS CHRYSANTHEMI. [Methods] Accelerated Solvent Extraction / Ion Chromatography was used to detect the SO2 residual in FLOS CHRYSANTHEMI. Alkaline solution was used as the extracting solution of grinded sample. After extraction by accelerated solvent extraction apparatus and purification by C18 solid phase extraction,the sample was isolated by IonP ac AS9- HC ion chromatographic column with carbonate as the leacheate. Detection was carried out by electrical conductivity detector. [Results] SO2 had good linear relationship within the range of 0. 5- 50 mg / L( r2= 0. 999 7). The quantitative lower limit( LOQ) and and detection limit( LOD) were 0. 17 and 0. 05 mg/L,respectively. With blank sample as the matrix,the average recovery rates at high,middle and low dosages were 82. 9%- 92. 6% with RSD( n = 6) less than 5. 0%. [Conclusions]Compared with the traditional method,this method had the advantages of high extraction rate and automation degree,and was suitable for the large-scale detection of SO2 residual in FLOS CHRYSANTHEMI. [Objective] To discuss the detection method for SO2 residual in FLOS CHRYSANTHEMI. [Methods] Accelerated Solvent Extraction / Ion Chromatography was used to detect the SO2 residual in FLOS CHRYSANTHEMI. Alkaline solution was used as the solution solution of grinded sample. After extraction by accelerated solvent extraction apparatus and purification by C18 solid phase extraction, the sample was isolated by IonP ac AS9- HC ion chromatographic column with carbonate as the leacheate. [Results] SO2 had good linear relationship within the The quantitative lower limit (LOQ) and the detection limit (LOD) were 0. 17 and 0. 05 mg / L, respectively. With blank sample as the matrix, the average recovery rates at high, middle and low dosages were 82. 9% - 92. 6% with RSD (n = 6) less than 5.0%. [Conclusions] Compared with the traditional method, this method had the advantages of high extraction rate a nd automation degree, and was suitable for the large-scale detection of SO2 residual in FLOS CHRYSANTHEMI.