•A new integrated process for the mercury removal and reclaim from the flue gas in the presence of SO2 was developed.•The laws of fate of mercury in Stage I of the integrated process were studied and revealed.•HgSO4 was determined as a more efficient absorbent on Hg0 removal and was introduced to Stage II of the integrated process.•1.0% H2O2 was introduced to the composite absorption solution to overcome the negative effect of SO2 on Hg0 removal in Stage II. A new integrated process was developed for the removal and reclamation of mercury from the flue gas in the presence of SO2, typically derived from nonferrous metal smelting. The new process contains a pre-desulfurization unit (Stage I) and a co-absorption unit (Stage II). In Stage I, 90% of the SO2 from flue gas can be efficiently absorbed by ferric sulfate and reclaimed sulfuric acid. Meanwhile, the proportion of Hg2+ and Hg0 in the flue gas can be redistributed in this stage. Then, over 95% of the Hg0 and the residual SO2 can be removed simultaneously with a composite absorption solution from the flue gas in Stage II, which is much more efficient for the Hg0 reclaiming than the traditional method. The composite absorption solution in Stage II, which is composed of 0.1g/L HgSO4, 1.0% H2O2 and H2SO4, could effectively remove and reclaim Hg0 overcoming the negative effect of SO2 on Hg0 absorption. Moreover, the concentrations of HgSO4 and H2O2 were adjusted with the changes in of the concentrations of Hg0 and SO2 in the flue gas. It is a potential and promising technology for the mercury removal and reclaim from the flue gas in the presence of SO2.