Abstract: Objective To understand correlation between obesity and metabolic syndrome in adolescents and provide evidence for the prevention and control of metabolic syndrome in this population. Methods A total of 214 subjects aged 14-26 years were selected in Beijing. Their body height, body weight, waist circumference, fat proportion (FAT%), blood pressure, Liver and kidney function, blood lipid and HbA1c were measured. According to the BMI, the subjects were divided into 3 groups: i.e. 99 subjects in normal group, 53 subjects in overweight group and 62 subjects in obese group. Metabolic syndrome was diagnosed according to IDF's definition. Trend chi-square test was used to compare the detection rates of different forms of metabolic syndrome and ROC curve was used to evaluate the roles of BMI, WC, WHtR and FAT% in diagnosis of metabolic syndrome. Results Metabolic syndrome was diagnosed in 21 subjects (9.8%), i.e. 14 boys (14.9%) and 7 girls (5.8%). The detection levels of ALB, TC, HDL-C, LDL-C, TG, hs-CRP, ALT, AST, UA, SBP, DBP were higher in obese group than in normal group, and differences were statistically significant (P0.05). There was positive correlation between TG, WC, SBP and DBP levels and BMI, WC, WHtR and FAT% levels,and there was negative correlation between HDL-C level and BMI, WC, WHtR and FAT% levels. FPG level was only positively correlated with BMI and WC levels. The biggest area under the ROC curve belonged to BMI, followed by WC. Conclusion The prevalence of different forms of metabolic syndrome and related risk factors increased with the increase of BMI in the adolescents and youths in Beijing. Among the four obesity evaluation indexes (BMI, WC, WHtR and FAT%), BMI and WC were closely related with different forms of metabolic syndrome, suggesting that early intervention should be conduct among adolescents and youths to reduce the prevalence of different forms of metabolic syndrome and related risk factors.