The invention discloses a flue gas low temperature denitration cobalt manganese oxide catalyst and a preparation method thereof, and belongs to the technical field of flue gas denitration catalysts. The active components of the catalyst comprise a cobalt oxide, a manganese oxide and a cobalt manganese oxide solid solution; the method is as follows: a cobalt salt and a manganese salt are used as raw materials, anhydrous sodium carbonate or ammonia water is used as a precipitant, first, a cobalt salt and manganese salt mixed water solution is prepared, then a precipitant solution is prepared, and a cobalt manganese oxide catalyst product is prepared. The method has the advantages of conventional raw materials, simple preparation method and the like; the cobalt manganese oxide catalyst prepared by the method has simple components, low cost, high NOx removal efficiency and other advantages. The method can be widely used for preparing the flue gas low temperature denitration cobalt manganese oxide catalyst, and the catalyst prepared by the method can be widely applied in low temperature removal of NOx in flue gas, and is especially suitable for low temperature removal of the NOx in the flue gas of a coal-fired power plant.