By using polyether grafted copolymer of acrylic acid/sodium methylacrylsulfonate as superplasticizer,the effect of the addition of polycarboxylate(PC) superplaslicizer on the structure of hardened cement paste was investigated.The content of water-reducer on the cement paste fluidity,water reducing rate of cement mortar,concrete slump and slump loss,and the compressive strength of mortar and concrete were also studied. The comparison between polycarboxylate superplasticizer and naphthalene-type water-reducer bought in the market was made.The experimental results show that polycarboxylate superplasticizer has excellent water reducing effect for the cement paste,cement mortar and concrete,and can remarkably enhance their fluidity and mechanical strengths.