Objective SIV30 protein of simian immunodeficiency virus ( SIV) was prepared by genetic engineering technique as an antigen diagnostic reagent, to establish an immune comb method for the specific detection of anti SIV IgG in monkey serum. Methods Recombinant expression plasmid of SIV SIV30 gene was constructed by prokaryotic expression vector pGEX-4T-1, and expressed in the competent BL21 cells. The recombinant protein was purified as a diagnostic antigen, and a standardized procedure for the detection of immune comb was established and applied for clinical detection. Results The optimum coating amount of antigen was 0.02 mg/ mL. The prepared IC was able to specifically detect the positive serum of SIV. There was no cross reaction between the sera of other viruses. It showed a high specificity of the detection method. Sensitivity analysis showed that the SIV30 protein was able to detect 1∶400 times diluted SIV positive sera. The result of stability and repeatability test (the same sample was repeated 3 times) showed that the coefficient of variation (CV) was less than 10%. The serum samples of 10 suspicious monkeys were detected by this method , showing a consistent rate of comb method and ELISA test result of 100%, Kappa = 1.000. Conclusions SIV30 protein is expressed in prokaryotic cells. The immune comb is prepared, and is successfullyl applied in clinical examination. It shows that the method has a high sensitivity, strong specificity, good reproducibility and practicability.