Abstract: Wave-absorbing material powder of the present invention has oxidation resistance and salt fog resistance, which includes an iron-containing wave-absorbing material powder, and a metal oxide ceramic layer and a metal phosphate layer sequentially coated on an outside of the iron-containing wave-absorbing material powder from the inside to the outside. A method for preparing the wave-absorbing material powder includes using atomic layer deposition to coat the iron-containing wave absorbing material powder with a metal oxide ceramic coating, and then adopting the atomic layer deposition to coat the metal oxide ceramic coating with a metal phosphate layer; repeating the above steps to form an alternating nano-stack of the metal oxide ceramic coating and the metal phosphate layer outside the iron-containing absorbing material powder; and finally performing a high-temperature annealing treatment.