Two charge transfer complexes of heteropolytungstate with Keggin structure, (C6H9N2O2S)3PW12O40·6H2O (SPW12) and (C6H9N2O2S)4SiW12O40·5H2O (SSiW12) were synthesized with 12-tungstophosphoric (silicic) acid and sulfanilamide in aqueous phase. The title complexes were characterized by means of elementary analysis, FTIR, UV, 1H NMR, XRD and TG-DSC. The results indicate that the title complexes are new heteropoly compounds, and the UV results reveal that there is a charge transfer interaction between sulfanilamide and heteropoly anion. Thermal analysis shows that the process of mass loss of the title complexes is carried out in four stages, and the two complexes begin to decompose at 272.8 ℃ and 330.4 ℃, respectively. The intermediates of the thermal decomposition were identified by FTIR. Antibacterial test results show that the title complexes both have good antibacterial activity, and the inhibition rate of SPW12 to Escherichia coli, Staphylococcus aurous is 73.28% and 99.36%, respectively.