Objective  To analyze the characteristics of adult body composition and obesity status of three ethnic groups: Ewenki, Daur and Mongolian Buryat. Methods   The bioelectrical impedance analysis（BIA）was used to measure 18 body composition components in three adults ethnic groups: 245 (male 124, female 121) Ewenki, 207 (male 90, female 117) Daur, and 181 (male 74, female 107) Mongolian Buryat . The data were processed using Excel 2016 and SPSS 24.0 statistical software. Results   The result  of correlation analysis showed that visceral fat level was significantly and positively correlated with age (P＜0.01). Stature, total body muscle mass, estimated bone mass and trunk muscle mass were all significantly and negatively correlated with age (P＜0.01) in males and females of the three ethnic groups. The percent body fat, percent left upper limb fat and percent trunk fat were positively correlated with age in Ewenki males (P<0.05 or P＜0.01) and the percent body fat, body mass index (BMI), percent limb fat and percent trunk fat were positively correlated with age in Ewenki females (P<0.05 orP>0.01). Body weight, BMI, percent left upper limb fat, left upper limb muscle mass, bilateral lower limb fat and muscle mass were all negatively correlated with age in Daur males (P<0.05 or P>0.01 ). Body weight, upper limb muscle mass and left lower limb muscle mass were negatively correlated with age (P<0.05 or P＜0.01) in Mongolian Buryat males and percent trunk fat was positively correlated with age (P<0.05) in Mongolian Buryat females. Comparison between ethnic groups showed that most of the body composition index values of the Ewenki and Mongolian Buryat divisions were closest to each other, and the body fat content was higher than that of the Daur. BMI, percent body fat and visceral fat level were all manifested in the Mongolian Buryat Department>Ewenki>Daur. Cluster analysis showed that Ewenki, Daur and Mongolian Buryat were closer to the northern groups and further from the southern groups.  Conclusion The Ewenki is most similar to the Mongolian Buryat in body composition characteristics all three ethnic groups has a more serious obesity problem.