The invention relates to an antirust oil composition used for metal processing and a preparation method thereof, solving the problems of poor antirust effect, over thick oil film, difficult removal and the like of the existing antirust oil. The antirust oil composition adopts 15-20% of base oil, 37.5-52% of petroleum sulfonate, 26-35% of high molecular carboxylic acid and soap, 4.5-7% of ester and 0.2-0.5% of benzotriazole and derivative as raw materials and is prepared by heating and stirring. The invention adopts the compounding of various corrosion inhibitors, exerts a complementary and accessorial ultra-effect composite action in the antirust performance, and generates major breakthrough in use performance and the effect, the antirust performance of the invention is far superior to the performance of antirust oil prepared from single agent and completely passes through the test and assessment of an optimizing antirust platform rack, and the invention has excellent moisture resistance and antirust functions, has excellent salt water erosion resistance, water replacement property, acid neutralizing performance and sweat control capability and reaches the quality requirement of athin multi-effect environment-friendly antirust oil complex additive.