Objective: To explore the anatomic features and the dissection technique of thyrothymic ligament (TTL) and to explore the clinical significance of protecting the inferior parathyroid gland (IPTG) with this structure. Method: Dissect the TTL of patients who receive initial thyroid surgery in our center, describe the structural features of TTL, and investigate the positional relationship of TTL and IPTG. Results: TTL is a kind of adipose connective tissue that is wide at the bottom and narrow at the top, accompanying with the inferior thyroid vein, from the thymus to the thyroid. Over 70% TTL are attached to the lower pole and the lower one-third dorsal of thyroid, containing fat and vessels. About 121 patients have undergone this dissection, totally dissected 194 sides, 143 sides had TTL (73.7%). About 63.4% IPTGs are located in the thymus-thyrothymic ligament-IPTG complex (TLIC), and nearly 70.6% IPTG can be proactively identified and located by the TTL during the operation. The incidence rate of postsurgical hypoparathyroidism is 14.9%. According to whether the dissection is successful, the IPTG can be described into 2 types, the ligament type (L) and the non-ligament type (N), and each type can be described into different subtypes.