A new type of antifouling polycarboxylate water reducer(PCA SF) with a snowflake shaped side chain was synthesized using the molecular structure optimized design of esterification and polymerization reaction. The effect of montmorillonite(MMT) on interlayer and surface adsorption of PCA SF was analyzed by FTIR,XRD and SEM. The effect of PCA SF on the fluidity of cement paste, the compressive strength and shrinkage of concrete that contains montmorillonite was studied. The results show that PCA SF molecules are adsorbed on the interlayer and surface of montmorillonite. Compared with ordinary polycarboxylate water reducer(PCA 1),PCA SF expands the interlayer spacing of montmorillonite,narrows the interface transition area between montmorillonite and cement stone,increases the compatibility with montmorillonite, enhances the strength of concrete containing montmorillonite and reduces its shrinkage.