Influence of varieties of sulfate and its use level on dispersing properties of different kinds of polycarboxylate superplasticizer was investigated, the dispersion mechanism of sulphate for polycarboxylate superplasticizer was explored and the improvement measures was recommended through determination of fluidity of cement paste,total organic carbon（TOC） and ζ potential with different types of sulphate added in cementitious materials. The results show that dehydrate calcium sulphate would decrease the water reduction ratio that different kinds of polycarboxylate superplasticizer can achieve when the use level of calcium dihydrate sulphate reached above 3.6% of the total mass of cementitious materials; the use level of Na2SO4 have significant impact to the fluidity of the cement paste with these three different kinds of polycarboxylate superplasticizer added; the cement paste loses its fluidity when the use level reaches 1% of the total mass of cementitious materials. When the use level of Na2SO4 reaches 3% of gelled materials, TOC of the solution decreases by 23%. The addition of Ba2NO3 could make TOC content recovered to the extent when the solution is not mixed with Na2SO4, and the fluidity also would get improved. The electrophoresis experiments indicate that the addition of sodium sulphate has great influence on the ζ potential, the more the use level, the smaller the absolute value of ζ potential and the poorer the dispersity. When Ba2NO3 is added, the absolute value of ζ potential would be raised a lot.