This work aims to prepare an environmental-friendly bio-based carbon steel protective agent to solve the disadvantages of traditional metal surface treatment method such asenvironmental pollution and damage to human health.Tannic acid, phytic acid, gallic acidand tartaric acid extracted from plants were blended with water to obtain a bio-based carbon steel protective agent TPA with excellent corrosion resistance. The carbon steel surface was coated to obtain the passivation film. Vianecessary analysis methods such as FTIR, OM, HSS, EIS, the effects of different kinds, ratios and concentrations of bio-based protective agents on the corrosion resistance of metals were investigated. Different bio-based phenolic hydroxy acids, such as tannic acid, phytic acid, gallic acid and tartaric acid, had anti-corrosion and protection functions for carbon steel, among which, phytic acid and tannic acid had good corrosion resistance. The bio-based protective agent TPA, which was prepared by blending phytic acid with tannic acid, had the best corrosion resistance. When the ratio of phytic acid and tannic acid and concentration of TPA were turned to be 2∶1 and 3%, respectively, the electrochemical impedance modulus of carbon steel treated by TPA can reach 5.02´107 Ω∙cm2, which was much higher than that of a single bio-cased phenolic hydroxy acidprotective agent (<1.0´104 Ω∙cm2). In conclusion, tannic acid and phytic acid in bio-based carbon steelprotective agent TPA form molecular association composite protective agent through hydrogen bonding. TPA protective agent can react with iron ions to form a dense passivation film, which overcomes the defects of stress cracking of tannic acid passivation film and porosity of phytic acid passivation film, and significantly improves the corrosion resistance of TPA passivation film. The bio-based carbon steel protective agentcan be used for anti-corrosion protection of carbon steel packaging materials