The invention relates to denitrition catalyst with a mercury removal effect. The catalyst has a chemical general formula of: MXn-V2O5-Y/TiO2, wherein, M is a metallic element selected from Fe, Cu, Mn or Co, X is halogen Cl or Br, Y is WO3 or MoO3, and n=2-4, and the elements are in a weight ratio of: 1-10 of M, 1-1.5 of V, 7.5-8.5 of W or Mo, and 75-100 of TiO2. The catalyst is prepared by the steps of: dipping V2O5-WO3/TiO2 or V2O5-MoO3/TiO2 with MCln or MBrn, then conducting frying and calcination. With the catalyst of the invention, catalytic reduction of NOx and catalytic oxidation of Hg<0> can be simultaneously completed in an original flue gas denitrition catalytic reactor, and the generated divalent mercury ions are washed and cured in desulfurized gypsum in a subsequent flue gas wet desulphurization process. Thus, cooperative control of the discharge of NOx and Hg<0> can be realized without increasing flue gas purification facilities of coal-fired power plants.