Abstract: Polycarboxylate superplasticizer with carboxylic，sulfonation groups in its main chain and polyoxyethylene ether as side chains was prepared by the macromolecular reaction. The structure of the superplasticizer was characterized by IR，1H NMR. A series of methods were proposed to characterize superplasticizer solution used in cement slurry by measuring surface tension，adsorptive power，conductivity and fluidity of cement slurry. The results showed that the superplasticizer as water-reducer can decrease the surface tension and can be adsorbed on the surface of cement particles to decrease surface energy，resulting in excellent dispersing ability of cement particles.