The in vitro biodegradability,granule appearance,crystal structure and chain length distribution of potato starches after lintnerization by mild acid (2.2 mol/L hydrochloric acid) were investigated. The results showed that the amount of rapidly digestible starch (RDS) increased accompanied by a corresponding decrease of resistant starch (RS),while slowly digestible starch (SDS) content was kept fairly constant. The granular shape of potato starch was destroyed and small fractions formed. Lintnerization increased the x-ray intensities and crystallinity of starches,but the x-ray diffraction patterns remained B-type. The ratio of 1 047/1 022 cm-1 also increased. A single peak DP 16 appeared in the chain length distribution. The amorphous regions of starch granules including both the amorphous lamellae and amorphous background were degraded after lintnerization,and the slow digestion property of potato starch may be associated with the crystalline lamellae.