Radioactive iodine therapy (RAIT) is one of the main treatment methods for patients with papillary thyroid carcinoma (PTC). Peripheral blood samples were collected from 29 PTC patients who underwent total thyroidectomy 1-2 days before RAIT (RAIT-0), 30 days after (RAIT-30), and 90 days after (RAIT-90). Flow cytometry was used to detect the absolute counts of peripheral blood lymphocyte subpopulations, and the Proximity Extension Assay (PEA) was used for targeted proteome quantification. We found that after RAIT, peripheral blood lymphocyte subpopulations and the abundance of inflammation-related proteins in PTC patients changed and did not return to pretreatment levels for a long time. The immune pathway "Cytokine-cytokine receptor interaction" related to cytokine signaling may be activated. In addition, there were two types of protein trends that were similar to the lymphocyte count trends. The five proteins with the greatest degree of trend change were MCP-1, TRAIL, TGF-alpha, Flt3L, and IL15. In RAIT-30 vs RAIT-0, B cells were significantly negatively correlated with protein Flt3L, and Th17 cells were significantly positively correlated with protein CRTAM. MCP-1, TRAIL, IL15, Flt3L, TGF-alpha, and CRTAM may be potential marker proteins for immune recovery in PTC patients after RAIT.