Objective To investigate the clinical features, electrophysiological characteristics and treatment of stiff-person syndrome (SPS). Methods Medical records were retrospectively collected from 8 SPS patients to analysis their clinical features, laboratory studies, electromyography characteristics and treatment effect. Results All 8 patients presented with classic SPS, experienced progressive muscle stiffness, rigidity and spasm with paroxysmal exacerbation, which most frequently involved the thoracolumbar paraspinal muscles and bilateral lower limbs and other parts of body including thoracic and abdominal wall, upper limbs, neck, head and face. Five patients underwent electromyography and the results showed continuous motor unit activity (CMUA) in the involved muscles at rest. CMUA reduced markedly in 2 cases after intravenous diazepam. Anti-glutamic acid decarboxylase (GAD) antibody testing was positive in one of 5 tested cases. All 8 patients experienced partially symptomatic relief for their muscle rigidity and spasm after benzodiazepines. Combined immunotherapy further attenuated the symptoms in two cases receiving intravenous immunoglobulin (IVIG) and one case receiving glucorticosteroids, respectively. Symptoms were completely relieved following thymectomy in 2 cases with thymoma. Conclusion SPS is characterized by progressive muscle stiffness, rigidity and spasm with paroxysmal exacerbation affecting the axial trunk and bilateral lower limbs most frequently. Electromyography indicates CMUA in these involved muscles at rest. Treatment with benzodiazepines combined with immunotherapy can improve the neurological manifestations. Thymectomy can completely relieve symptoms of SPS in patiens with thymoma.