The invention discloses a novel cerium oxide denitration catalyst. The novel cerium oxide denitration catalyst has the expression formula of CeNaOx, wherein the molar ratio of Ce to Na is (90-98):(10-2), and x is balanced and determined by positive and negative valence electrons in each atom. The preparation method of the catalyst comprises the following steps of: 1, dissolving cerous sulfate, sodium phosphate and cerium sulfate in water at normal temperature, and stirring to form a transparent solution; 2, transferring the prepared solution into a hydrothermal reaction kettle, and adding deionized water; 3, sealing the hydrothermal reaction kettle and transferring the hydrothermal reaction kettle to an oven for heating and reacting, reducing the temperature, performing centrifugal separation, and cleaning until no sulfate radical is detected by using deionized water; and 4, drying and roasting the centrifuged precipitate, thereby obtaining the catalyst. The metallic oxide catalyst is in the range of 200-500 DEG C, and the purification efficiency of nitric oxide is 71-100 percent; and the composite oxide catalyst has high high-altitude-resistant speed and good alkali-resistant metal poisoning performance, the efficiency is greatly improved, and the operating cost can be obviously reduced.