Abstract: A series of Co₃O₄/eggshell catalysts with different Co₃O₄ contents were prepared by the deposition-precipitation method using discarded eggshells as supports, and tested for the catalytic reaction of N₂O decomposition on a fixed-bed continuous flow micro-reactor. The activity test results show that the catalyst exhibits higher activity towards N₂O decomposition when the mass fraction of Co₃O₄ is 20%, with a specific activity of 4.3 times to that of pure Co₃O₄ (reaction temperature 440 ℃). At the same time, it shows strong resistance to 3% O₂, 3.3% H₂O and/or 2.0×10⁻⁴ NO in feed. Various characterization results indicate that the predominant composition of eggshell is CaCO₃, which has a close incorporation with Co₃O₄. The strong interaction between CaCO₃ and Co₃O₄ contributes to producing more oxygen vacancies and Co³⁺ in the 20% Co₃O₄/eggshell catalyst. The redox performance of Co₃O₄ is improved, and the Co−O bond is effectively weakened. In addition, it helps to increase the strength and amount of basic sites on the catalyst surface, making it easily transfer electrons and promote N₂O decomposition.