To further understand the interaction between polycarboxylate superplasticizers(PCE) and the mineral phases of cement, the effect of PCE with different structure on the electronic state and the morphology of the hydration products of tricalcium silicate(C3S) were investigated by XPS and SEM. The results show that, the intensity of C1s photoelectron of C—H in the sample with adsorbed PCE enhanced obviously, and the C1s spectrum of C—O appeared. However, the intensity of Si2p photoelectron of the samples with adsorbed PCE reduces greatly and the adsorption thickness was in the range of 094nm to 140nm. The attenuation degree of Ca2p XPS scanning spectrum was small because the adsorption layer was filled with calcium. In addition, all the samples with adsorbed PCE have chemical shift in different extent and the chemical shift increases with the decrease of the side chain density. According to the SEM results, the PCE could hinder the adhesion of the hydration products of C3S. Besides, the hydration degree of C3S will decrease with the decrease of the side chain density.