Abstract: Objective:To calculated the lowest concentration of analyte detected by nucleic acid blood test system based on Probit regression,and verify the consistency between the analytical sensitivity of nucleic acid testing reagents in routine use in blood station laboratories and the declaration in reagent specifications to ensure the quality of nucleic acid testing.Method:Nucleic acid reagents were used to detect the sensitivity of serum plates for nucleic acid series analysis.The repeated detection rates of HBV-DNA,HIV-RNA,HCV-RNA and other samples were calculated.Using the Probit module of SPSS statistical software,the 95% detection limit of each item was calculated.Result:The detection limit of HBV-DNA,HIV-RNA and HCV-DNA was 4.568 IU/ml,46.000 IU/ml and 46.600 IU/ml repectively,which were all better than the 95% limit stated in the reagent specification.Conclusion:Based on Probit regression,nucleic acid reagents can be used to detect the sensitivity of serum plate of nucleic acid series analysis.The detection limit of 95% of the items can be calculated accurately,and the sensitivity of laboratory analysis can be directly judged within the acceptable range.