The invention relates to a method for preparing an SCR deNOx catalyst. The method comprises: 1. dissolving a certain amount of ferrous sulfate in water; 2. adding anatase type nanometer TiO2, wherein the mass ratio of ferrous sulfate to the TiO2 is 1: (2-30); 3. adding a silicate nanoporous material, wherein the mass ratio of the silicate nanoporous material to the TiO2 is 1 : (0.5-2) to stir evenly; 4. heating and stirring the obtained solution until the solution is dried, and drying the solution for 1 to 10 hours at a temperature of between 60 and 160 DEG C; and 5. burning the dried solution in the step 4 by oxygen for 0.5 to 5 hours at a temperature of between 200 and 350 DEG C, and calcining the dried solution in the presence of nitrogen at a temperature of between 350 and 450 DEG C for 4 to 48 hours to obtain the catalyst. Furthermore, the invention also relates to the SCR deNOx catalyst prepared by the method for preparing the SCR deNOx catalyst. The catalyst has arsenic poisoning resistance and sulfur oxidizing resistance, can be formed through various processes, and is applicable to electrical power and related enterprises in flue gas selective catalytic denitration and other energy environment-friendly industrial fields.