Abstract: Objective To analyze the clinical characteristics of mitochondrial encephalomyopathy in children and its diagnostic methods. Methods Clinical manifestations, laboratory findings, genetics, neurophysiology, pathology and imaging of 13 children with mitochondrial encephalomyopathy were retrospectively analyzed. Results The Main clinical manifestations of mitochondrial encephalomyopathy were seizure（92.3%）, vomiting（38.4%）, headache（38.4%）, ataxia（38.4%）, dysarthria（30.7%）, mental regression（30.7%）, limb weakness（30.7%）, dystonia（30.7%）, abnormal tendon reflex（53.8%）, paroxysmal hemiparalysis（23%）, heart disease（23%）, visual abnormalities（23%）, etc. The disease was diagnosed based on the findings of fatigue test, neurophysiology, imaging, genetics, and muscle biopsy. Conclusion Since mitochondrial encephalomyopathy in children is characterized by multiple and complex clinical manifestations, it should be early diagnosed based on a comprehensive analysis of its clinical manifestations and laboratory findings.