Abstract: In order to establish a new and simple determination method of amylose and amylopectin in Panicum miliaceum L. and enrich its related research on physical and chemical properties, the paper used dual-wavelength colorimetric method and the absorption spectra of amylose/amylopectin-I₂ complexes to determine the measuring wavelength and reference wavelength firstly. The contents of amylose and amylopectin in sample solution were determined according to the linear regression equations. Measure wavelength and reference wavelength of amylose determined by the wavelength scanning graph were 613 nm and 520 nm, respectively. Measure wavelength and reference wavelength of amylopectin were 538 nm and 700 nm, respectively. The result showed that linear relationship of amylose and amylopectin concentrations were in the range of 0-0.15 mg/mL and 0-0.125 mg/mL. The amylase and amylopectin contents of 15 kinds of Panicum miliaceum L. were measured using the method in lab. Through the precision and recovery experiment, amylose and amylopectin were measured 6 times and the standard deviation was 0.145 and 0.022, respectively, the recovery range was 85.3%-97.9%. Test results met the analysis requirement. Dual-wavelength method was simple, rapid and accurate and was suitable to determine amylose and amylopectin in Panicum miliaceum L.. The method could evaluate Panicum miliaceum L. taste and quality, and then screen palatability of excellent variety.