Abstract: ¹²⁵I-HSA-IFNα2b was prepared with Ch-T method. The labeling yield is 82.72%, the radiochemical purity is 95.53%, and the specific activity is 0.26 MBq/μg. The antiviral activities of ¹²⁵I-HSA-IFNα2b are almost same as HSA-IFNα2b analyzed with WISH/VSV system in vitro. After SD rats injected with¹²⁵I-HSA-IFNα2b subcutaneously, the radioactivity in urine and faeces in seven different periods of 0-6, 6-12, 12-24, 24-48, 48-96, 96-192 and 192-300 h shows that ¹²⁵I-HSA-IFNα2b is excreted mainly by kidneys, partly by diachorema, and average accumulation excretory rates of 300 h in urine and feces are 80.10% and 16.00%, respectively; the radioactivity in bile in seven periods of 0-1, 1-2, 2-4, 4-6, 6-12, 12-24 and 24-30 h shows that ¹²⁵I-HSA-IFNα2b also can be excreted by bile after being metabolized by liver, and average accumulation excretory rate of 30 h in bile is only 1.61%.