Abstract: The influence of preparation processes such as stirring time of slurry,dispersant content,solids loading and p H value on viscosity of Si C aqueous paste were investigated. The results show that the slurry viscosity decreases with increasing stirring time and levels off when the stirring time exceeds 24 hours; the slurry viscosity decreases with increasing dispersant content but increases when the dispersant content exceeds a certain quantity; when the solid loading is higher than 30%,the slurry viscosity increases sharply and doesn't decrease even if the dispersant content is increased; when the p H value is above5. 5,the slurry viscosity increases rapidly with increasing p H value and slightly declines when the p H value exceeds 8. 15. By optimizing the preparation processes,the Si C aqueous slurry with viscosity of about 1. 0 Pa·s and 30% solid loading could be prepared.