The invention provides a preparation method of a selective catalytic reduction (SCR) catalyst Mn-Ce-M/TiO2 by removing NOx from flue gas, wherein M represents one or more of composite oxides, namely Fe, Co, Cu, Cr, Zr and Al, the molar ratio of the elements is Ti: Mn: Ce: M =1:(0.005-1):(0.005-1):(0-1). In the invention, an improved coprecipitation method is adopted, and an intermediate compound, namely titanium nitrate Ti(NO3)4 is taken as a precursor of TiO2, thus the influence of the other impurities in the precipitation process is overcome; by changing the dispersing homogeneous degree of MnOx and CeO2 on the surface of a carrier TiO2, the activity of the catalyst is improved and the temperature of the SCR reaction is reduced; by adjusting the preparation condition of the TiO2 precursor, the sulfur resistance and water resistance of the catalyst are improved completely; and by adding the elements, such as Fe, Co, Cu, Cr, Zr and Al and the like, the activity and resistance of the catalyst are further modified.