Magnesium hydroxide (Mg(OH)_2) was a kind of inorganic chemical products widely used as industrial retardant owing to its unique physical and chemical properties, while the agglomeration usually inhibited its applications. Thus the study of dispersion of Mg(OH)_2 was the research hotspot recently. This paper studied the fabrication of dispersive Mg(OH)_2 plates via treating agglomerated Mg(OH)_2 in NaOH solution at room temperature, using the irregular agglomerated Mg(OH)_2 plates with a primary size of 0.5-3.0μm and an average agglomerated size of 12.5 μm as the raw material. The experimental results indicated that after treating the raw material in 5.0 mol.L-1 NaOH solution for 72.0 h, which improved the crystallinity, inhibited the exposuring of (101) polarity plane and promoted the exposuring of (001) stable plane via dissolution-recrystallization route. Thus prompted the conversion of the agglomerates to the dispersive Mg(OH)_2 plates with a primary size of 0.2-1.0μm, an average agglomerate size of 2.3μm.