Effects of different sulfates on Marsh time, shear stress, and apparent viscosity of cement paste with polycarboxylate type (PC) superplasticizer were investigated. Through a series of micro measurements, it was indicated that with abundant SO2-4 in the cement paste, the adsorption amount of PC superplasticizer increased. The results show that sulfates with alkali ions(such as Na2SO4 and K2SO4) have a pronounced negative effect on the dispersity of PC superplasticizer, while the effect of indissolvable sulfate (such as CaSO4·2H2O) on the dispersity of PC superplasticizer is slight.Large amount of SO2-4 contributed to the declining dispersity of PC superplasticizer, and the increasing amount and strength of flocculent structure in cement paste.