Objective: To investigate the rationality of bilateral central lymph node dissection for unilateral differentiated thyroid cancer. Methods: 80 cases of unilateral differentiated thyroid cancer patients were all treated with radical thyroidectomy combined with bilateral central lymph node dissection, and the central lymph node metastasis and postoperative complications of patients were analyzed. Results: Among 80 patients, ipsilateral central lymph node metastasis in 32 patients (32/80, 40.0%), contralateral central lymph node metastasis in 8 cases (8/80, 10.0%), simultaneous metastasis of bilateral central lymph nodes in 16 cases (16/80, 20.0%). The total contralateral lymph node metastasis rate was 30.0% (24/80), the total lymph node metastasis rate was 70.0% (56/80). 9 (9/80, 11.3%) patients suffered temporary hypocalcemia, 8 (8/80, 10.0%) patients suffered temporary recurrent laryngeal nerve injury after operation. All the 80 patients were followed up for 3 years without recurrence or metastasis. Conclusions: Ipsilateral central lymph node is the most easily metastatic site of unilateral differentiated thyroid cancer, but contralateral central lymph node also has possibility of metastasis and skip metastasis. Bilateral central lymph node dissection for unilateral differentiated thyroid cancer can remove potential metastatic lymph nodes effectively and determine metastasis of the tumour, which is benefical for reducing recurrence after operation and guiding postoperative staging.