The invention discloses a long-acting rust-proof rust-conversion agent for a metal surface, and belongs to the technical field of anti-corrosion materials. The long-acting rust-proof rust-conversion agent comprises the components by the weight percentage: 30-50% of carrier oil, 1-4% of an osmotic stabilizer, 6-10% of a slow-release carrier, 3-5% of a sterilization agent, 1-2% of an antioxidant, 2-6% of a thixotropic agent, 10-20% of phytic acid, 9-15% of gallic acid, and 6-20% of polyaniline, wherein the sum of the amounts of the components is 100%. The product has the advantages of environmental protection, no toxicity, flexible, simple and convenient construction technology and low requirement grade of surface treatment, is used in port and pier facilities, offshore platforms, power plant steel frames, storage tanks, pipeline valves and the like, and can provide long-acting and lasting corrosion prevention and protection functions; an anti-corrosion layer has the advantages of strongadhesive force, good densification isolation properties, prominent synergistic protective effect, and strong permeability and chelating rust-conversion and rust-inhibition abilities; the long-actingrust-proof rust-conversion agent can effectively eliminate or inhibit microbial corrosion, so as to achieve permanent corrosion prevention and protection on a metal structure in a variety of harsh environments.