The invention relates to an I<131> labeled anti-human neuropilin receptor-2 (NRP-2) monoclonal antibody E4. The antibody E4 is labeled by I<131> through a chloramine T labeling method. The I<131>-E4 is produced through the following steps: 1) preparing the antibody E4, NaI<131>, and PBS being 7.4-7.6 in pH value, and adding the components into an EP tube, adding newly-prepared chloramine T and rapidly vibrating and uniformly mixing the liquid, performing a reaction at room temperature, and adding a newly-prepared reduction agent, sodium metabisulfite, to terminate the iodination reaction; 2) moving out the reaction liquid, and measuring the labeling rate of a labeled product through TLC, normal saline being a developing solvent; 3) treating the reaction liquid on a Sephadex G25 column to purify the reaction liquid with PBS being about 7.4 in pH value as an eluting solution to prepare I<131>-E4. Advantages of the radionuclide are integrated with the antitumor cell humanized monoclonal antibody, so that the targeting property and molecular imaging effect of the medicine are improved. The antibody E4 can increase the early-stage diagnosis rate and monitor treatment effect of positive tumor expressed by the NRP-2, has a wider available range and is suitable for imaging positive tumors expressed by the NRP-2 in all stages.