To correctly understand the clinical characteristics of undifferentiated thyroid carcinoma and to explore ways to improve the survival rate. Retrospective analysis of clinical data of 58 patients with undifferentiated thyroid cancer and squamous carcinoma revealed that the invasion was more extensive, and the 1- and 3-year survival rates of all patients with undifferentiated thyroid cancer were 37.8% and 31.2%, respectively. The prognosis of undifferentiated thyroid cancer is poor, but radical surgical resection and postoperative ≥60 Gy improve its survival rate. Local recurrence is the leading cause of death. Undifferentiated thyroid cancer has the worst prognosis among all types of thyroid cancer, with a 5-year survival rate of only 5%-15%. Large cell carcinoma, small cell carcinoma, squamous cell carcinoma, giant cell carcinoma, adenoid cystic carcinoma, mucinous carcinoma, and poorly differentiated papillary and follicular carcinomas with higher malignancy originating from the thyroid gland can be classified as undifferentiated carcinoma. In this study, we retrospectively analyzed the clinical data of 58 patients with undifferentiated and squamous thyroid carcinoma admitted to our hospital from March 1981 to July 2005, in order to correctly understand the clinical characteristics of undifferentiated thyroid carcinoma and explore the methods to improve its survival rate. The scope of surgical resection was mainly lobar + isthmus resection, and different surgical styles were used according to the different organs involved. For tracheal invasion, tracheal tumor debridement or partial tracheal resection with clavicle flap repair is used; for esophageal invasion, myelomeningocele or/and partial esophageal mucosa resection is performed; for upper mediastinum involvement, sternal split tumor resection or palliative resection is performed; for less invasion of upper mediastinum, the clavicle head can also be resected to expose the field for tumor removal; for encircling common carotid artery, the tumor is resected by preserving the common carotid artery as much as possible, otherwise, palliative resection is performed. Otherwise, the tumor can be removed palliatively. The anterior cervical muscles should be resected accordingly according to whether they are invaded and the extent of invasion; the internal jugular vein tumor embolus should be resected as cleanly as possible; the recurrent laryngeal nerve can be resected if it has been paralyzed, while those without paralysis should be dissected and protected as much as possible. The treatment of lymph node metastasis in the neck depends on whether the primary foci are cleaned or not.