Abstract: Sodium metasilicate pentahydrate and sodium metasilicate nonahydrate,which meet the standard HG/T 2568—2008,were synthesized with rice husk as raw material.This technological process contains the pretreatment,energy recovery by the combustion,dissolution reaction,formation reaction,crystallization and so on.Effects of reaction factors,such as combustion temperature of rice husk,amount of sodium hydroxide,dissolution reaction time,starting reaction temperature,modes of cooling crystallization,seed crystal,and surfactant,were investigated and optimum conditions were confirmed as follows:combustion temperature of rice husk was 600 ℃,reaction time of rice husk ash with sodium hydroxide was 4 h,prograss cooling time was 7 h,and mass fractions of adding the seed crystal and the surfactant were 1% and 0.1%~0.3%,respetively.Under the optimum conditions,composing of sodium metasilicate pentahydrate prepared by this method was as follows:mass fraction of Na<SUB>2</SUB>O and SiO<SUB>2</SUB> were 28.4% and 28.8% respectively,white content was 74.1%,and melting point was 72 ℃ while the composing of sodium metasilicate nonahydrate was:mass fraction of Na<SUB>2</SUB>O and SiO<SUB>2</SUB> were 21.4% and 20.5% respectively,white content was 96.4%,and melting point was 51 ℃.