Objective To study the nonalcoholic fatty liver disease (NAFLD) and blood lipid metabolism and its related factors in school-aged obesity children in Lanzhou. Methods Grades 1~6 pupils aged 7 to 14 were selected from 3 schools.BMI were chosen as normal control.Abdominal ultrasound was taken, and 5 mL fasting venous blood samples was collected to detect aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma glutamyl transpeptidase (GGT), total cholesterol (CHOL), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C) and low density lipoprotein cholesterol (LDL-C). Results A total of 80 obese children were detected from 3 000 children.Compared with 51 normal controls, AST, ALT, GGT, CHOL, TG, LDL-C were higher while HDL-C was lower in obese children (P<0.05).AST, ALT, GGT, TG, LDL-C as the risk factors and was positively associated with NAFLD while HDL-C as the protective factors and was negatived.The detection rate of obese children with NAFLD was 27.5% (22/80);The control group did not detecet NAFLD, the incidence of obese children with NAFLD was obviously higher than that of normal children (P<0.05).Compared with the obesity group without NAFLD, AST, ALT, GGT, TG were higher while HDL-C was lower (P<0.05). Conclusion Obesity can lead to liver damage, blood lipid metabolic abnormalities, even the occurrence of nonalcoholic fatty liver disease in school-aged children, NAFLD could increase liver function damage and lipid metabolism disorders furtherly.