Abstract: The dispersion state of silica hydrosol, water glass and ethyl silicate hydroly-sate is studied by ²⁹SiNMR spectrography. The results indicate that all silica hydrosols are typical colloidal solution. The state of silica in water glass is more complicated. It is in true solution when the mole ratio of SiO,/Na,O is equal to or less than 2, but colloidal behaviour becomes gradually apparent when the mole ratio is more than 2.The state of silica in the hydrolysate is dependant on the mole ratio of H₂O/C₂H₅O; when the ratio is less than 0.5, the product is poly-exthoxysilicate in the solution and when the ratio is equal to or more than 0.5, the product consists of small particulate colloids and polycyclic silicic acids in the solution.