O'Sullivan-Mcleod syndrome is a very rare variant of MND with a good prognosis. Its clinical feature is distal lower motor neuron syndrome of both upper limbs, and there is no effective treatment at present. We reported a case of O'Sullivan-Mcleod syndrome in this paper.The patient exhibited with middle-aged progressive distal muscle weakness and atrophy of both upper limbs, without sensory, cognitive or behavioral impairment and without pyramidal tract sign. Laboratory examination, imaging and genetic tests showed no obvious abnormalities. EMG revealed neurogenic damage to the small muscles of both hands. Now we retrospectively analyzed the clinical features of a patient with O'Sullivan-McLeod syndrome, and data from 18 cases for comparative analysis, in order to improve its understanding by clinicians.