Disclosed are a grain boundary and surface-doped rare earth manganese-zirconium composite compound as well as a preparation method and use thereof. A rare earth manganese oxide with a special structure is formed at grain boundary and surface of a rare earth zirconium-based oxide by a grain boundary doping method so as to increase oxygen defects at the grain boundary and the surface, thereby increasing the amount of active oxygen, improving the catalytic activity of the rare earth manganese-zirconium composite compound, inhibiting high-temperature sintering of the rare earth manganese-zirconium composite compound, and improving the NO catalytic oxidation capability. When the rare earth manganese-zirconium composite compound is applied to a catalyst, the consumption of noble metal can be greatly reduced.