The patient was a 68-year-old woman who was admitted to the hospital with “episodic ankylosis of the trunk and both lower extremities for 2 years and 2 months”. The patient developed ankylosis of the left lower extremity without any obvious cause two years ago, which could not be bent and affected walking, and gradually involved the right lower extremity and trunk. The above-mentioned symptoms are easy to occur after hearing a sudden sound, emotional tension and violent force on the limbs, and are relieved after resting and calming down, and do not occur during sleep, and both upper limbs are not involved. He was diagnosed as “dystonia” and “anxiety somatization disorder” and was given oral medroba and meperidine, but his condition did not improve. The symptoms have not improved. The mobility disorder of both lower extremities fluctuates, remitting-exacerbating-remitting-exacerbating, and the symptoms have increased significantly in the past two months. Physical examination: normal vital signs, cranial nerves (-), normal muscle strength of the limbs, normal tendon reflexes, no percussive muscle tonic response, no involuntary movements, no muscle bundle tremor and subcutaneous creeping waves. The right lower extremity had increased muscle tone and bilateral Babinski’s sign (+). The whole body deep and superficial sensation was normal. Ancillary tests: EMG did not show neurogenic and myogenic damage. Anti-nuclear antibody titer 1:1000 and positive anti-adhesion site antibody. Serum anti-glutamic acid decarboxylase antibody assay (GAD-Ab) was positive. Diagnosis: stiff person syndrome. stiff-person syndrome is a rare neurological disorder characterized by excessive contraction of trunk and lower limb muscles with myalgic muscle spasms, with an incidence of 1 in 1 million. Because of its rarity, it is easily misdiagnosed and missed. Current effective treatments are benzodiazepines, baclofen, levetiracetam, gammaglobulin, and plasma exchange. This patient’s symptoms improved rapidly after the administration of clonazepam and levetiracetam. It is important to note that stiff person syndrome is often combined with autoimmune disease and is sometimes seen as a paraneoplastic syndrome that can be associated with ovarian tumors and requires frequent and regular checkups.