Abstract: Flame retardant magnesium hydroxide was prepared by precipitation method with MgCl2·6H2O as raw material and NaOH as precipitant.To solve the filtration difficulty of the magnesium hydroxide slurry，it proposed to add surfactants in the preparation process. The effects of feeding mode，surfactant types，and dosage on the filtration performance of magnesium hydroxide slurry were investigated.The chemical composition of product was analyzed by chemical analysis method.The morphology was characterized by transmission electron microscopy.Results showed that the filtration performance of the magnesium hydroxide slurry was significantly increased when double dropping mode was used，sodium alcohol ether sulphate（AES）was as the surfactant and its dosage was 4%（mass fraction），and the quality of magnesium hydroxide meet the standard requirement of Magnesium Hydroxide for Industrial Use（HG/T 3607—2007， class Ⅰ）.Transmission electron microscopy results showed that the product had hexagonal flake morphology with an average particle size of 50 nm，and no agglomeration.

Key words: magnesium hydroxide, surfactant, filtration, slurry, agglomeration