The invention discloses an antirust agent containing modified mullite powder. The antirust agent containing the modified mullite powder is prepared from the following raw materials by weight: 80-100 parts of castor oil, 3-5 parts of lanolin metallic soap, 8-10 parts of aluminium stearate, 1-3 parts of ferrocene, 0.8-1.0 part of polyisobutene, 1-2 parts of 2-cyanoethyl formamide, 0.5-1.0 part of tetrazole, 0.8-1.2 parts of 2-aminoethyl heptadecenyl imidazoline, 1.0-1.5 parts of N-phenyl-2-naphthylamine, 1-3 parts of zinc dialkyl dithiophosphate, 1-3 parts of polyvinyl alcohol, 5-8 parts of sodium citrate, 8-10 parts of ammonium borate, 2-4 parts of sodium dodecyl benzene sulfonate, 5-6 parts of a film-forming resin and 1-3 parts of the modified mullite powder. By adding the modified mullite powder and adjusting the formula, the antirust agent having a very good gas phase antirust effect is prepared. The antirust agent provided by the invention has excellent antirust performance and is convenient for use; and the production process is simple.