Objective To develop a scale-down model in the purification process for effectively evaluating the lifetime of chromatography medium in the production process of recombinant Mycobacterium tuberculosis fusion protein(EC), providing technical basis and optimization strategies for industrial production.MethodsBased on the principle of linear scaling, a 156-fold scale-down column model was constructed. The reliability of the scale-down model was evaluated by comparing key performance indicators such as chromatogram, protein recovery rate, removal rate of host protein, removal rate of residual antibiotics, removal rate of exogenous DNA, and electrophoretic purity between the scale-down model and commercial production scale. On this basis, the scale-down model was used to perform 40 cycles of chromatography purification, and the chromatographic performance data of the target product was analyzed to evaluate the long-term effectiveness of the chromatography medium.ResultsThe chromatographic performance indicators of the scale-down model and commercial production scale, including chromatogram features, protein recovery rate, host protein removal rate, and electrophoretic purity, were highly consistent with excellent data stability. After 40 cycles, the protein content, purity, residual host protein,antibiotic activity, and residual exogenous DNA of the target product all met the quality standards. The column efficiency(HETP, As) of the chromatography column met the process requirements.ConclusionThis study successfully verified the effectiveness of the scale-down model and determined that the chromatography medium lifetime is tentatively set at 40 cycles, providing reliable technical support for industrial production.