Based on the adsorption of Hg

0

on the manganese based catalyst surface

the adsorption mechanism of mercury（Hg

0

） from the flue gas was theoretically discussed with the method of density functional theory（DFT）

including the adsorption mechanism of Hg

0

on the surface of pure TiO

2

MnO

x

/TiO

2

Hg

0

and SO2 on the s

urface of MnO

x

/TiO

2

. For each structure

the geometry optimization

the energy calculation

the bond length and the size of adsorption energy were calculated using density functional theory calculation method of the GGA-PBE. The results indicate that the adsorption energy of Hg

0

on the surface of TiO

2

（001） is generally small

so Hg

0

does not have strong interaction with the substrate. On the surface of Mn base

Mn can enhance the ionic nature of mercury. The adsorption position of SO2 on MnO

x

/TiO

2

（001） surface is complex

and the structure with the lowest energy can be determined by calculation. When Hg and SO2 are simultaneously placed on the surface of Mn base

it is found that SO2 and Hg

0

was competitive on the MnO

x

/TiO

2

（001） surface.