Digested resistant starches of mung bean, potato, Castanea henryi and Castanea mollissima were made, and the changes of intestinal flora and their structure before and after in vitro fermentation were studied. The results showed that those digested resistant starches had good proliferative effect on bifidobacterium and lactobacillus, while they had inhibitory impact on Escherichia coli and Clostridium perfringens, and no obious influence on Enterococcus faecalis, Corynebacterium fusifome and facultative bacterial. The increasing total acidities of fermentation liquids demonstrated that the digested resistant starches could be used by intestinal probiotics. In comparison with the digested resistant starches before fermentation, the digested resistant starches after fermentation had more lower average degree of polymerization, but had more greater specific surface areas and densities, which might improve their absorption capacities and play important roles in the other physiological functions. Crystal types of digested resistant starches after fermentation turned into type A, and their microcrystalline degrees reduced.