How to cost-efficiently and cooperatively remove SO2, NO and Hg0 in flue gas is a hot topic in the field of air pollution control. This work developed an integrated system that consists of a dual-absorption system and a vapor oxidation system, in which Na2CO3 and H2O2/Na2S2O8 were used as the absorbent and oxidant. The results indicated that the efficiencies of SO2 removal and NO conversion reached 99.5% and 93% respectively. Rising the vaporization temperature and decreasing the pH of H2O2/Na2S2O8 could facilitate the NO conversion. The spent Na2CO3 after desulfurization was demonstrated to be a good absorbent for NO2 removal. The best conditions of pH and temperatures for the dual-absorber were determined as 10/8 and 60/60 °C, respectively. The presence of 1000 mg/m3 SO2 and 300 mg/m3 NO favored the Hg0 removal. TMT-15, an organic sulfur compound, was demonstrated to be useful in retaining Hg2+, with an efficiency of 92%. According to the analyses of electron spin resonance (ESR), ion chromatography (IC), atom fluorescence spectrometry (AFS) and X-ray photoelectron spectroscopy (XPS), SO4− and HO were proved to be the key radicals, and the existing forms of N- and Hg- species in the product were identified as NaNO2/NaNO3 and HgCl2.