Objective To study the radiolabeling of anti-progastrin-releasing peptide single-chain antibody (anti- ProGRP(31-98)scFv) with 131I and evaluate its stability, immunological activity and biodistribution. Methods The anti-ProGRP(31-98)scFv was labeled with 131I by Chloramine-T method, and purified by gel column separation method. The labeling efficiency, radiochemical purity and stability were estimated by using paper chromatography. The immunological activity of radiolabeled antibody was detected with cell conjugation assay. The biodistribution of 131I-anti-ProGRP(31-98) scFv antibody was carried out in Kunming mice. Results The labeling efficiency and radiochemical purity of 131I-anti-ProGRP(31-98)scFv were 93.35±0.67% and 98.49±1.21%, respectively. The immunobinding ratios of 131I-anti-ProGRP(31-98)scFv for NCI-H446 cells and A549 cells were 85.36±1.45% and 21.02±2.16%, respectively（P<0.05）. The 131I-anti-ProGRP(31-98)scFv antibody was mainly digested through liver and kidney and with rapid elimination in blood. Conclusion 131I-anti-ProGRP(31-98) scFv has high labeling efficiency and good stability, and also keeps good immunological activity. It mainly metabolize thought liver and kidney and with rapid elimination in blood.