〔Abstract〕 To analyze the physical and chemical properties of human gastric factor by bioinformatics method , and to express and purify the protein. Methods Protein online analysis software was used to predict the physical and chemical properties of gastric intrinsic factor and analyze their hydrophilicity and hydrophobicity. The online tool was used to predict and analyze the human gastric factor signal peptide and its subcellular location. The eukaryotic expression recombinant plasmid pcDNA3. 1 ( + ) ⁃human GIF⁃His tag was constructed , and the gastric intrinsic factor was purified by nickel column after expression in HEK293F cells. The purity and activity of purified gastric intrinsic factor were verified by SDS⁃PAGE , Western blot and indirect ELISA. Results Gastric factor con⁃tained 417 amino acids and was a hydrophilic acid stable protein. It was a secreted protein with Sec original signal peptide. pcDNA3. 1( + ) ⁃human GIF⁃His tag recombinant plasmid was successfully constructed and soluble expres⁃sic factor is successfully prepared , and the bioinformatics results show that the protein is a hydrophilic acid stable secreted protein , laying a foundation for the subsequent use of this protein as an immunogen and protein calibrator to construct an immunoassay for gastric factor.