OBJECTIVE： To study the effects of superfine grinding on the powder properties and dissolution of oyster shell， and to provide experimental basis for its comprehensive exploitation. METHODS： Oyster shells were firstly prepared into ordinary powder by grinder. Then the ordinary powder was prepared into micro-powder Ⅰ （crushing 5 min） and Ⅱ （crushing 10 min） by ultrafine pulverizer. The differences of micromeritic properties were investigated before and after superfine grinding from the aspects of particle size distribution， specific surface area and porosity， angle of repose， bulk density， hygroscopicity， etc. Scanning electron microscope （SEM）， Fourier transform infrared spectroscopy （FTIR） and X-ray powder diffraction （XRD） techniques were used to analyze the morphological characteristics and chemical structure of oyster shell before and after superfine grinding. The dissolution were investigated. RESULTS： Compared with ordinary powder， micropowder Ⅰ and micropowder Ⅱ’s were small in particle size and uniformly distributed， but the particles were easy to adhere and aggregate； the specific surface area， porosity and the angle of repose increased， while bulk density decreased； the hygroscopicity increased. FTIR and XRD showed no significant change in chemical structure of oyster shell after superfine grinding. The dissolution rate of micropowder Ⅱ and micropowder Ⅰ was 18.5％ and 10.3％ at 10 min， and the dissolution of ordinary powder was only 6.4％ at 60 min. CONCLUSIONS： Compared with ordinary powder， oyster shell show obvious differences in powder properties after superfine grinding； the dissolution rate of the powders increases， and there is no significant change in chemical structure.