The invention relates to a preparation method of high-chromium doped ferriferrous oxide powder. The molecular formula of the above material is Fe3-xCrxO4. The preparation method comprises the following steps: 1, preparing Cr doped Fe3O4 precursor powder through adopting a co-precipitation technology: slowly dropwise adding a precipitant to a FeSO4 and Cr2(SO4)3 mixed solution which is stirred, carrying out natural precipitation after titration is completed, drying the obtained precipitate, taking out the dried precipitate, and uniformly grinding the precipitate to obtain the precursor powder; 2, carrying out compaction molding on the precursor powder, carrying out first Fe foil coating, then carrying out vacuum sintering, taking out the obtained sintered product, and grinding the sintered product to obtain powder; and 3, adding Fe2O3 powder to the powder obtained in step 2, uniformly grinding the powders, carrying out compaction molding on the obtained powder mixture, carrying out second Fe foil coating, then carryin gou vacuum sintering, taking out the sintered mixture, and uniformly grinding the sintered mixture to obtain the required content Cr doped ferriferrous oxide powder Fe3-xCrxO4 (x is 1 to 1.5). The preparation method of the high-Cr doped ferriferrous oxide powder which cannot be prepared in the prior art is provided to conveniently research the performances of the tube wall surface oxide film of a nuclear power plant major loop system austenitic stainless steel tube.