Abstract: Dual wavelength method was applied to determination of amylose and amylopectin from american ginseng under ice-temperature storage. According to the principle of dual-wavelength spectrophotometry and scanning spectra,the contents of amylose and amylopectin in american ginseng under ice-temperature storage were determined at the selected wavelengths of 630 and 520 nm with respective reference wavelengths of 423 and 771 nm. The regression equation of the standard curve of amylose and amylopectin were y=23.046x+0.0062 and y=2.5021x-0.0017 with respective correlation coefficient R² of 0.998 and 0.997. According to methodological validation experiment,the RSD of the stability were 1.95% and 1.85%,the RSD of the precision were 0.89% and 0.42%,the RSD of the precision were 0.82% and 0.62%,and the average recovery rates were 100.22% and 100.19%,respectively. Thus,dual-wavelength method was simple,rapid and accurate. And it showed that the contents of amylose and amylopectin in american ginseng decreased slightly with the increasing of storage months.