A series of V2O5-xCeO2/AC (noted as V-Ce/AC) catalysts were synthesized by the impregnation method, which combined the advantage of AC and V-Ce. The effects of SCR atmosphere on Hg0 removal were systematically investigated at low temperature. The experimental results indicated that NO had a positive effect on Hg0 removal. In addition, an interesting experimental phenomenon was found that NH3 also showed a positive effect on Hg0 removal, which is different from many studies that have reported a negative effect of NH3 on Hg0 removal by other catalysts. NH3-TPD experiment showed that there was no apparent competition between NH3 and Hg0. An FT-IR gas analyzer and in situ DRIFTS were used to study the mechanism for the effect of NH3 on the catalyst surface and found that a small part of NH3 was overoxidized to NO2 in this catalytic system. O2 acted as a promoter in the whole process of NO and Hg0 removal. However, H2O showed an inhibiting effect on Hg0 and NO removal over V-Ce/AC catalysts, which may be caused by the competitive adsorption of H2O and pollutants (NO and Hg0). Additionally, 1 V-8Ce/AC catalyst exhibited high stability ( EHg = 87.6%, ENO = 82.84%) after 72 h reaction in SCR atmosphere at 150 °C.