Objective To investigate the changes in plasma very long chain fatty acids (VLCFAs),and to explore its relationship with obesity-related index in obese children.Methods One hundred and sixty-six obese children aged 7 to 12 years old were investigated and 148 health children matched with age and sex were selected as control group.Their height,weight,and waist circumference (WC) were measured.The percentage of body fat (PBF) was tested by dual-energy X-ray absorptiometry.Fasting blood triglycerides (TG),total cholesterol (TC),high density lipoprotein-cholesterol (HDL-C),low density lipoprotein-cholesterol (LDL-C) levels,fasting plasma glucose,and fasting insulin (FINS) were determined.The body mass index (BMI),BMI-Z score,waist to height ratio (WHtR),and homeostasis model assessment for insulin resistance (HOMA-IR) were calculated.The plasma VLCFAs were analyzed by gas chromatography-mass spectrometry.Results (1) Compared with normal control children,body weight,BMI,BMI-Z score,WC,WHtR,PBF,TG,TC,LDL-C,FINS,and HOMA-IR in obese children were increased (all P ＜ 0.05),and the level of HDL-C was decreased (P ＜ 0.05).(2) The plasma levels of docosamonoenoic acid (C22 ∶ 1 n-9) and arachidonic acid (C20 ∶ 4n-6) were decreased while the levels of arachicacid (C20 ∶ 0) and eicosapentaenoic acid (C20 ∶ 5n-3) increased in obese children compared to non-obese children.(3) The linear correlation analysis showed that PBF was positively correlated with C20 ∶ 0 and C20 ∶ 5n-3,and negatively correlated with C20 ∶ 4n-6.WHtR was negatively correlated with C22 ∶ 1 n-9 and positively correlated with C20 ∶ 0 (4) The multiple stepwise regression analysis showed that C20 ∶ 0 was the main factor for PBF,and C22 ∶ 1 n-9 and C20 ∶ 0 were the main factors for WHtR.Conclusion The metabolic abnormality of plasma very long chain fatty acids exists in obese children.The changes in C20 ∶ 0,C22 ∶ 1 n-9,and C20 ∶ 5n-3 may be associated with obesity in children.