Abstract: In this paper the crystallinity of starch granules and the effect of swelling in water at normal temperature on starch granules were studied by weans of X-ray diffraction examination.The results indicated that there existed a kind of sub-crystal in corn,cassava or potato Starch Granules,and that there were two different types of crystalline structure in native starch granules.It was pointed out that the inner structure of native starch granules could include.non-crystal,sub-crystal and crystal,and that the inner structure of any starch granules could be determined to include either one or two,or three of the three types.

Key words: Starch Crystal Sub-crystal Non-crystal