Abstract: The surface modification of industrial SiC powders was carried out by polyethyleneimine(PEI), and the effects of pH and adding content of PEI on flow characteristics of the powder before and after modified treatment were analyzed. The results were:when pH of PEI is 6.5 and the mass fraction of PEI is 3%, the modified SiC powder possessed better flow characteristics, more saturation adsorption on the powder surface, more dispersive and uniform particle size distribution and shape.