〔Abstract〕 Objective To compare the efficacy of sternocleidomastoid intermuscular approach (SMIA) thyroidectomy and linea alba cervicalis approach (LACA) thyroidectomy in patients with thyroid tumor (TT). Methods A total of 90 TT patients admitted to Xiamen Hospital of Traditional Chinese Medicine from June 2018 to June 2021 were selected and divided into SMIA group and LACA group, with 45 cases in each group according to different surgical plans. Patients in the LACA group received LACA thyroidectomy, and patients in the SMIA group received SMIA thyroidectomy. Perioperative indexes, incidence of complications, postoperative pain score, aesthetics score, quantitative indexes of trauma before and after surgery, and immune function indexes of the two groups were compared. Results The incision length, operation duration and hospital stay in the SMIA group were shorter than those in the LACA group, and the intraoperative blood loss was less than that in the LACA group, with statistically significant differences (P < 0.05). At 6 h, 12 h, 1 d and 3 d after surgery, visual analog scale (VAS) score in the SMIA group was lower than that in the LACA group, and the difference was statistically significant (P < 0.05). At 1, 3 and 6 months after surgery, the Vancouver scar scale (VSS) score in the SMIA group was lower than that in the LACA group, and the difference was statistically significant (P < 0.05). On day 1 and 3 after surgery, the levels of serum interleukin-6 (IL-6), norepinephrine (NE), C-reactive protein (CRP) and adrenocorticotropic hormone (ACTH) in the two groups were increased compared with those before surgery, and the differences were statistically significant (P < 0.05). The IL-6, NE, CRP and ACTH in the SMIA group were lower than those in the LACA group, and the differences were statistically significant (P < 0.05). On day 1 and 3 after surgery, the levels of CD3+ , CD4+ and CD4+ /CD8+ in the two groups were lower than those before surgery, the differences were statistically significant (P < 0.05), and CD3+ , CD4+ and CD4+ /CD8+ in the SMIA group were higher than those in the LACA group, the differences were statistically significant (P < 0.05). The total incidence of complications in the SMIA group was 4.44%, lower than 20.00% in the LACA group, and the difference was statistically significant (P < 0.05). Conclusion Compared with LACA thyroidectomy for TT patients, SMIA thyroidectomy has more advantages in optimizing perioperative indicators, alleviating postoperative pain, reducing complications and improving scar aesthetics, and has less impact on the body's traumatic stress response and immune function.