The water content of brucite is particularly high, about 31%; the differential thermal analysis of brucite shows that the temperature of thermal decomposition dehydration is between 420 ~ 520 ℃, which is close to the combustion temperature of general articles, so it can be used as fire retardant coating and flame retardant. Brucite, as a new type of filled flame retardant, can reduce the surface temperature of the synthetic material in the flame by releasing the combined water and absorbing a large amount of latent heat when it is heated and decomposed. It has the function of inhibiting polymer decomposition and cooling the combustible gas produced. The flame retardant based on brucite has good flame retardancy and reinforcement, and it is non-toxic, pollution-free and weathering resistant. It is also suitable for high temperature molding process.