The complications of thyroid fine needle aspiration biopsy (FNAB) have been long observed, but the knowledge of some rare complications is still improved. In this case report, a rare complication of acute transient thyroid swelling (ATS) shortly after FNAB was reported for the first time in the Chinese mainland. The patient showed an obvious swelling of the neck and suffered from acute pain less than 20 minutes after aspiration. Immediate thyroid ultrasound examination showed diffuse swelling of the entire thyroid gland with heterogeneous echo changes. 17 hours later, the repeated examination showed the thyroid was restored. Pathology of FNAB showed some atypical thyroid follicular epithelium and the final pathology showed it was papillary carcinoma. We also reviewed the literature and preliminary concluded that ATS was a sudden and rare complication of FNAB with a rapid self-repair result, while the reason for ATS was still unknown and further puncture for the diffuse altered area is necessary to explore the physiopathologic mechanism.