The invention relates to a catalyst carrier, an SCR denitrifying catalyst of electric plant flue gas that is prepared by the catalyst carrier and a preparation method of the SCR denitrifying catalyst. The invention adopts purple mud clay and anatase TiO2 to form the carrier; by weight, the content of the TiO2 is 50 to 99 percent and the content of the purple mud clay is 1 to 50 percent. The catalyst carrier can further contain active carbon, CaSO4 and ammonia-typed Y molecular sieve, which respectively account for 0 to 20 percent of the weight of the catalyst carrier. The active ingredients of the catalyst comprise V2O5 accounting for 1.0 to 6.0 percent of the weight of the catalyst, WO3 accounting for 4.0 to 10.0 percent of the weight of the catalyst, MoO3 accounting for 0 to 9.0 percent of the weight of the catalyst, and CeO2 accounting for 0 to 2.0 percent of the weight of the catalyst. The working temperature of the catalyst is 200 to 500 DEG C, has high catalytic activity, large specific surface and strong toxin immunity, hardly has inactivation phenomenon in long-time running, and is insensitive to vapor and sulfur dioxide.