The invention discloses a MnOOH nanorod denitration catalyst and a preparation method thereof. The catalyst comprises a MnOOH nanorod and CeO2 attached to the MnOOH nanorod. The preparation method comprises the following steps: carrying out a solvothermal reaction on potassium permanganate and N,N-dimethyl formamide at the temperature of 100-200 DEG C for 2-4 hours to obtain the MnOOH nanorod; adding absolute ethyl alcohol and nanometer CeO2 particles into the reacted solution, and ultrasonically stirring for 3-5 hours, so that the nanometer CeO2 particles are fully loaded to the MnOOH nanorod; and performing solid-liquid separation on the impregnated product, and washing and drying to obtain the MnOOH-CeO2 composite catalyst. The preparation method is simple in process and simple and convenient to operate, industrial production is conveniently realized, the catalyst does not have toxicity and is high in safety, and harm of the used catalyst to the environment is reduced.