The particle size of ultrafine magnesium hydroxide is about. 100nm~1000nm, Ultrafine magnesium hydroxide has active surface-free energy, magnesium hydroxide is used to form coacervate, its particle size is about 10-100μm. In this thesis, according to the quality of the raw material and the demand of the production, the whole experimental process includes two sections.In the first section, the results reveal that some factors, for example filtration of ammonium chloride, composition of hydrothermal s...