Abstract: The main chemical component of diatomite is amorphous silica.Preparation technology of sodium silicate by water-heated alkali reaction and with Linjiang low-grade diatomite after mineral processing was studied.The influences of the time and temperature of alkali-dissolved reaction，mass ratio of liquid to solid and mass ratio of sodium hydroxide to diatomite on the dissolution rate of silica as well as on Si/Na ratio of sodium silicate were investigated.Results showed that dissolution rate of SiO2 improved and the Si/Na ratio decreased obviously as the mass ratio of sodium hydroxide /diatomite increased under the same conditions.It was verified that the optimal experiment results：dissolution rate of SiO2 was 93.22%，Si/Na ratio of sodium silicate was 0.96，and the output ratio of sodium silicate was 169.35 g when diatomite was 100 g  under the conditions as following: time of alkali-dissolved reaction was 90 min，the temperature of alkali-dissolved reaction was 96 ℃，mass ratio of liquid to solid was 2.5，and mass ratio of sodium hydroxide /diatomite was 1.24. 

Key words: purified diatomite, water-heated alkaline reaction, sodium silicate