The invention belongs to the technical field of catalysts, in particular to a load-type LaBO3 (B=Mn, Fe) perovskite selective reduction of NOx with NH3 and a preparation method thereof. In the invention, a citric acid sol-gel method is combined with a wet process dipping method to prepare a carrier-loaded citric acid complex precursor, and the precursor is roasted at high temperature to obtain the load-type perovskite catalyst. The catalyst can be used for selective reduction of NOx with NH3, the good effect is obtained, the higher conversion rate at lower reaction temperature is achieved and the defect of the high reaction temperature of the traditional catalyst is eliminated.