The particle size, microstructure and dissolution of functional components of mulberry leaf powder with different fineness were measured. The three kinds of mulberry leaf powder was obtaind, fine powder, micro powder, and superfine powder. Compared with fine mulberry leaf powder, the average particle size of micro mulberry leaf powder and superfine powder decreased by 86.82% and 91.39% respectively. The content of DNJ (1-deoxynojirimycin) increased by 107.86% and 118.75% (P<0.01), and the content of total phenolics increased by 0.40% and 4.91%. Moreover, the content of polysaccharides increased by 18.86% and 36.57% (P<0.01), and the content of flavonoids increased by 28.47% and 31.86% (P<0.05)，with the contents of amino acid nitrogen increased by 20.00 % and 45.00 %. The Soluble dietary and total dietary fiber increased by 3 998.31% and 6 809.12%, 324.84% and 554.92% (P<0.01). Insoluble dietary fiber decreased by 53.31% and 86.59% (P<0.01). Therefore, the fine pulverization increases the amount of the functional properties dissolution.