Abstract: Cobalt based organic framework (Co-MOF) material was synthesized by hydrothermal method with cobalt ion in cobalt nitrate hexahydrate Co(NO₃)₂ ·6H₂O as the central metal ion and homophenic acid (H₃BTC) as the organic ligand. And the Co-MOF was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The prepared Co-MOF was doped in rosin-based alkyd resin, which was coated on the surfaces of Q235 mild steel electrode and tinplate to obtain coating samples. The effect of the dosage of Co-MOF on the corrosion protection of the coating was investigated by electrochemical test and salt-spray test. The results showed that proper addition of Co-MOF could increase the corrosion protection of the coating, but excessive Co-MOF was easy to cause agglomeration of particles, reducing the protective effect of the coating. When the Co-MOF dosage in the rosin-based alkyd resin was 0.2 g (about 0.1% of mass fraction), the corrosion current density was 1.63×10^-6 A/cm², and the protection efficiency reached 99.2%. The corrosion current density of the coating without Co-MOF was 29.10×10^-6 A/cm², and its protection efficiency was only 85.4 %.