Dual-wavelength spectrophotometry was applied to determine the amylose and amylopectin content in lotus root from Hanzhong with iodine as coloring agent. According to the color characteristics of amylose mixed with iodine forming blue mixtures and amylopectin mixed with iodine forming amaranth mixtures, and the determination results of Dual-wavelength spectrophotometry, the determination and reference wavelength of amylose were 511 nm and 582 nm,respectively,Y=0.046 43 x+0.011 67(r2=0.998 7); the determinat...