Heteropolyacids and their salts have been effectively used in selective catalytic reduction because of the Keggin structure and extraordinarily strong acidity. Catalysts with and without the Keggin structure were synthesized to further investigate the effects of heteropolyoxometallate on low temperature NH3-SCR. XRD, BET, Raman, H-2-TPR, NH3-TPD, FT-IR, and SO2-TPD techniques were used to characterize the physicochemical characteristics of the catalysts. Results indicate that catalysts with the Keggin structure had more surface Bronsted and Lewis acid sites, and these catalysts had significantly improved performances in the SCR reaction and in SO2 poisoning resistance. [GRAPHICS] .