Poly(aspartic acid) (PASP) as environmental friendly and biodegradable polymer has been considered to replace polyacrylic acid (PAA) for years. In this work, effect of polyvinylpyrrolidone (PVP) on the rheological properties on aqueous SiC suspensions dispersed with PASP was investigated. PASP (0.3wt%) and PVP (0.1wt%) co-stabilized suspensions at different pH and solid loadings can achieve better dispersion at lower dosages of dispersants than those with only PASP (0.7wt%). The complex of anionic PASP molecules and nonionic PVP molecules through intermolecular hydrogen bonding provided enhanced steric hindrance, and resulted in improved stability.