We aimed to explore the mechanism of postoperative sore throat and dry throat by monitoring cuff pressure of two endotracheal tubes in thyroid surgery. Fifty patients who underwent thyroidectomy surgery were included. They were randomly divided into the NIM group and Rusch group. Patients in the NIM group were assigned with the Medtronic Xomed NIM endotracheal tube and the Rusch enhanced endotracheal tube for the Rusch group. After induction of general anesthesia and endotracheal intubation, cuff pressure was raised up to 20 mmHg (28 cm H2O) by inflation. Cuff pressure was recorded per 5 minutes until extubation. Throat complaints of sore throat and dry throat were assessed and graded 24 h later. The NIM group showed higher cuff pressure compared with the Rusch group (31.1 +/- 9.5 mmHg vs. 23.0 +/- 8.5 mmHg, P < 0.001). The NIM group got higher sore throat score than the Rusch group (4.0 +/- 2.0 vs. 2.6 +/- 1.4, P < 0.01). Multiple linear regression model analysis suggested that cuff pressure had obvious effect on sore throat (ss = 0.391, SE = 0.162, P < 0.05). There was no significant difference in the dry throat classification of the two groups in nonparametric test (P > 0.05). However, the rates of dry throat events of I and II grades of NIM group were lower than those in Rusch group [grade I: 6 cases (22.2%) vs. 8 cases (34.8%); grade II: 3 cases (11.1%) vs. 8 cases (34.8%)]. The rates of dry throat events of grades III and IV in NIM group were higher than those in the Rusch group [grade III: 6 cases (22.2%) vs. 3 cases (13.0%); grade IV: 12 cases (44.4%) vs. 4 cases (17.4%)]. Decision tree model analysis suggested when cuff pressure < 24.1 mmHg, the risk of dry throat of grade I was higher; when 24.1 mmHg <= cuff pressure < 28.4 mmHg, the risk of dry throat of grade III was higher; when cuff pressure = 28.4 mmHg, the risk of dry throat of grade IV was higher. Compared with the Rusch group, the NIM group had higher cuff pressure and the postoperative sore throat among patients was more severe. Sore throat VAS score was associated with the mean cuff pressure, but dry throat grade was not associated with mean cuff pressure.