Effects of five kinds of waterreducing agents, calcium lignosulfonate(CLS), modified calcium lignosulfonate(GCL16A), aminosulfonic based superplasticizer(ASP), sulfonated naphthalene formaldehyde(FDN） and sulfonated melamine urea formaldehyde resin(SMUF), on the durability of cement mortars were studied including impermeability, carbonization depth and shrinkage. The research results indicate that durability of cement mortar mixed with SMUF is the most excellent; durability of cement mortar mixed with GCL16A and FDN is next; that mixed with CLS is the weakest.