Objective To explore the clinical manifestation, diagnosis and prognosis of Leigh syndrome in children. Method Clinical data from 4 cases of Leigh syndrome conifrmed by genetic testing were retrospectively analyzed. The related literature were reviewed. Results In 4 cases, 3 were boys and one was a girl, 3 cases were onset in infant and one case was in school age. The main manifestations were mental retardation, low muscle tone, convulsions, feeding dififculties, drooping eyelids, extraocular muscle paralysis and nystagmus, irritation, activity intolerance etc. The brain magnetic resonance imaging (MRI) revealed symmetry long T1, T2 abnormal signal in brainstem, bilateral globus pallidus, thalamus, cerebellar dentate nuclei, and periaqueductal, 3 cases involved midbrain, one case involved thalamus, and one case involved cerebellar dentate nuclei;2 cases had encephalatrophy. Electromyography was normal in all cases. The levels of lactate in blood and cerebrospinal lfuid were increased. Mitochondrial DNA (mtDNA) detection found the mutation of mtDNA 8993 T>G in one case, and the mutation of mtDNA 9176 T>C in another 3 cases. The case onset in school age died of respiratory failure one month later, and another 3 cases were still in follow up, there were mental retardation, but no signiifcant setback. Conclusion The clinical manifestations of Leigh syndrome in children are diverse. The diagnosis is based on the typical clinical manifestations and MRI, blood and/or cerebrospinal lfuid lactate levels. The genetic testing is the golden standard for diagnosis.