Abstract: A novel comb-like poly(styrene-co-maleic anhydride)-graft-poly(stearyl alcohol-co-hexanediol-co-decanedioic acid) (SMA-g-PSHD) was designed and synthesized,which was used as the surface modifier for dispersing CaCO₃ in organic medium.The comb-like copolymer was absorbed on the surface of CaCO₃ using the anionic polycarboxylate as binding group while dispersed in organic medium using the low polarity PSHD polyester side chains.The structure,composition and molecular weight of SMA-g-PSHD were determined by FT-IR,¹H-NMR and GPC,respectively.The dispersion ability of CaCO₃ in organic medium,the rheological behavior and stability of CaCO₃ suspension using SMA-g-PSHD as the dispersant were investigated systematically.The results showed that the addition of SMA-g-PSHD improved the dispersion ability of CaCO₃ in xylene significantly and decreased the apparent viscosity of CaCO₃ suspension dramatically who behaved near Newton fluid.In addition,the SMA-g-PSHD modified suspension showed superior stability.