The aim of the study was to investigate whether carbon nanoparticles (CNs) can improve the dissection of lymph nodes and protect parathyroid glands (PGs) during reoperation for patients with papillary thyroid carcinoma (PTC).PTC patients who previously underwent thyroidectomy and later received reoperation between January 2009 and January 2016 were retrospectively recruited. We compared the patients who had CN suspension injected into the residual thyroid gland with a control group of patients who did not have the injection. The primary endpoints were the number of lymph nodes dissected, the number of PGs identified and reimplanted, and the rate of postoperative hypoparathyroidism.CN suspension injection was conducted in 55 of 174 patients. The total number of lymph nodes and metastatic lymph nodes dissected between the 2 groups were not different (22.8 ± 13.7 vs 21.0 ± 13.3, P = .481 and 5.5 ± 3.8 vs 4.8 ± 4.0, P = .695). The number of central lymph nodes and metastatic central lymph nodes in the CN group was significantly higher than those dissected in the control group (8.7 ± 6.9 vs 6.2 ± 5.2, P = .037 and 2.7 ± 1.9 vs 2.1 ± 1.6, P = .012). More PGs were identified (2.42 ± 1.15 vs 1.58 ± 1.12, P = .001) and fewer were reimplanted (48 vs 90, P = .040) in the CN group. Patients who had CN suspension injection had a lower rate of transient hypoparathyroidism (14/55 vs 50/119, P = .043) but no significant difference in the rate of permanent hypoparathyroidism (1/55 vs 9/119, P = .173).CN suspension injection improves dissection of central lymph nodes and identification of PG in PTC patients undergoing reoperation and lowers the rate of postoperative transient hypoparathyroidism.