The aqueous SiC slurry for gelatin gelcasting was prepared by submicron SiC, gelatin and TMAH as the main raw material. The effects of pH, sintering aid, dispersant, gelatin and solid content on rheological properties were studied. The results show that 12 is the best pH value of slurry. Sintering aid slightly increased the viscosity of the slurry. 0.6wt% TMAH got the lowest viscosity. Effect of gelatin concentration on viscosity is not obvious, and increasing the content of gelatin solution, the viscosity of slurry decreased. The viscosity of the slurry increased with the increasing of the solid content. When pH is 12, the dispersant content is 0.6wt%, adding 20 wt% concentration of 10 wt% gelatin, the SiC slurry can get the 55 wt% solid content, viscosity of 132 mPa.s which is conducive to the gel casting.