In accordance with the difficult of SiC submicron-powders dispersed in water suspension，the single factor test is firstly used to study the effects of milling time and ultrasonic time on the dispersion of SiC submicron-powders in water suspension.Then the orthogonal test is used to study the effects of dispersant types，dispersant concentration and pH value on the dispersion of SiC submicron-powders in water suspension. And the absorbance is used to evaluate the dispersion of SiC submicron-powders. The results show that the effect of dispersant types on the dispersion of SiC submicron-powders in water suspension is the greatest，followed by the pH value, and the dispersant concentration is the minimum. The optimal dispersing condition is that the milling time is 60 min，the ultrasonic time is 30 min, the mass percent of PEI is 3.0%, and the pH value is 11.