Abstract: Abstract: Column chromatography is based on the difference of physicochemical properties of components in the mixture. The mixture is separated after multiple distributions by using the different distribution coefficients of each component in the stationary and mobile phase. The starch was hydrolyzed by amylase after retrogradation under high pressure and humidity. Then, the retrograde starch was dissolved by 4 mol/L potassium hydroxide and the solution was adjusted to neutral next. The precipitate of amylose was obtained by adding n-butanol to the solution. While, amylopectin was prepared by adding ethanol to the supernatant. Both of amylose and amylopectin in sweet potato were retrograded for the second time to narrow their molecular weight distribution. And column chromatography was used to separate the components furtherly. The total yields of amylose and amylopectin were more than 2.4% respectively. The results of visible spectrum and molecular weight distribution showed that Mw of amylose and amylopectin narrowed to 1641-2069 g/mol and 1671-2167 g/mol, respectively, while Mn narrowed to 1516-1710 g/mol and 1526-1678 g/mol. The corresponding PDI of amylose ranged from 1.082-1.209, and PDI of amylopectin ranged from 1.095-1.291. Artificial zeolite with 1-3 mm diameter was suitable for the separation of amylopectin, while artificial zeolite with 4-6 mm diameter was suitable for amylose. In the course of separation, amylose with higher DP adsorbed on the macrozeolite surface. It was eluted out from the mixture first for the weaker adsorption force. Amylose with lower DP entered into the small holes of macrozeolite, and was eluted out subsequently for the stronger adsorption force. When separated by small zeolite column chromatography, the amylopectin components of F1b with small molecular weight and high homogeneity were eluted out first. While, amylopectin components of F2b with large molecular weight and low homogeneity were eluted out first, indicating that the branching degree of amylopectin also played a certain role in the separation of starch components by zeolite column chromatography. X-ray diffraction showed distinctive spectra. Amylose components revealed strong sharp peaks at the diffraction angles (2θ ) of 18.9°, 23.4°, 27.2°, 29.3°, 32.3°, 33.7°. Amylopectin components showed obvious sharp peaks at around 21.6°, 22.9°, 23.9°, 26.5°, 27.1°, 29.3°, 34.1°, 35.8°, 39.5°. The molecular weight distribution index (PDI) of sweet potato amylose was close to 1.0 at the same time. Amylose and amylopectin with extreme narrow molecular weight exhibited sharp peaks like metallic salts. That could be used for the study of the spatial structure changes of starch macromolecules in depth. Micrographs showed that amylose was composed of many linear molecules and presented typical linear “wicker-like” morphology, while amylopectin showed “branch-like” shape. The results provide a simple and efficient method for the preparing of amylose and amylopectin with extreme narrow molecular weight distribution. It brings about favorable conditions for further exploring morphological changes of starch macromolecules during aggregation progress.