Abstract: The structure and properties of potato starch were investigated after superfine grinding with a fluidized bed jet mill. The particle size, granular morphology, functional groups, rheological property, thermal and physicochemical properties of the potato starch were characterized using laser particle size analyzer (LPA), scanning electron microscopy (SEM), X-ray photoelectron spectrometer (XPS), simultaneous thermal analyzer and rheometer. It was found that the particle size of potato starch was significantly decreased to 13.59±0.04 μm after superfine grinding. There was no new element peak in the spectrum of X-ray photoelectron spectroscopy (XPS), no new elements were introduced on the surface of starch granules. The amylose content increased, the molecular chain of amylopectin shortened, and the solubility, swelling degree and transparency of starch paste increased. The viscosity resistance decreases, and the apparent viscosity decreased. The hydrogen bonds and molecular chains of starch molecules were broken, and the retrogradation decreased. This study provides a theoretical basis and technical support for improving deep exploitation and utilization of potato starch.