Abstract: In this research,potato resistant starch was prepared from potato starch with method of microwave heat-moisture treatment. The effects of starch milk mass fraction,microwave power and microwave time on yield and structure of potato resistant starch were investigated. The maximum yield of potato resistant starch was 9.77% with the optimal conditions of microwave time 240 s,microwave power 750 W and starch milk mass fraction 15%. The results of scanning electron microscope(SEM),Fourier transform infrared spectrometer(FT-IR)and X-ray diffraction(XRD)indicated that the structural integrity of starch granules was destroyed,while the crystal structure was changed and the degree of crystallinity was increased. New functional groups were not formed from the sample prepared with microwave heat-moisture treatment method,but the intermolecular hydrogen bonds were altered.