【Objective】To observe the efficacy of metformin treatment on non-alcoholic fatty liver disease（NAFLD）in obese children.【Methods】A retrospective analysis was performed of 10 patients over 10 years old with NAFLD from July 10，2013 to August 23，2016. These patients were treated with metformin in pediatric endocrinology outpatient department of the First Affiliated Hospital of Sun Yat-sen University. The changes of liver ultrasonography，hepatic enzymes，blood lipids，blood glucose，insulin， HOMA-IR，BMI，and waist circumference height ratio were compared before and after treatment with metformin.【Results】There were 10 cases of NASH，including 5 boys and 5 girls. The short-term treatment of metformin reduced the levels of ALT，AST，and HOMA-IR for all 10 patients（P < 0.01）. ALT，gradually decreased with the course of treatment. Fasting insulin and waist circumfer? ence to height ratio also improved with the treatment（P < 0.05）；the changes of TG，BMI，and fast glucose were not obvious（P > 0.05）.【Conclusion】Metformin can effectively reduce liver enzymes and improve insulin sensitivity in children with NASH in short term，the improvement of TG and BMI in short term is not obvious.