Objective To study the prevalence and characteristics of overweight and obesity among Chinese adults aged 18 and above,in year 2010.Methods A total of 98 271 adults aged 18 and above,who were sampled from 162 surveillance points of 31 provinces of China mainland,were enrolled in the study.Weight and height of each subject were measured, and then body mass index (BMI) was calculated.Overweight was defined as 24 kg/m2 ≤ BMI ＜ 28 kg/m2,while obesity was defined as BMI ≥28 kg/m2.After complex weighting,the prevalence of overweight and obesity among total population and specified rates among different populations by gender and districts and age were calculated.Results Prevalence rate of overweight among Chinese adults was 30.6％,separately at 31.5％ and 29.7％among males and females (x2 =16.05,P ＜ 0.01 ) ; 27.1％,37.2％ and 32.3％ in groups of population aged 18 -44,45 - 59 and over 60 year-old,respectively ( x2 =482.00,P ＜ 0.01 ) ; separately at 33.9％and 29.1％ in urban and rural areas (x2 =21.14,P＜0.01 ); 32.0％,31.1％ and 28.0％ in eastern,central and western regions,respectively ( x2 =8.72,P ＜ 0.05 ).Prevalence rate of obesity among Chinese adults was 12.0％,separately at 11.9％ and 12.1％ among males and females ( x2 =0.33,P＞0.05) ; and 10.6％,14.7％ and 12.6％ in groups of populations aged 18 -44,45 -59 and over 60 year-old,respectively ( x2 =111.25,P ＜ 0.01 ) ; separately at 14.2％ and 11.0％ in urban and rural areas ( x2 =12.11,P＜0.01 ) ; and 13.5％,11.9％ and 9.9％ in eastern,central and western regions,respectively ( x2 =10.05,P ＜ 0.01 ).The total prevalence rate of overweight and obesity among Chinese adults was 42.6％.It appeared that the total prevalence rate of overweight and obesity among urban populations (48.1％ ) were higher than rural populations(40.1％ ) ( x2 =20.37,P ＜0.01 ) ; while the total rate showed a gradual decreasing trend from eastern(45.5％ ) to central(43.0％ ) and western(37.9％ ) regions( x2 =10.46,P ＜ 0.01 ).Conclusion The prevalence of overweight and obesity were comparatively high among Chinese adults aged 18 and above in year 2010,and significant differences could be found among gender,age,urban or rural areas and eastern,central or western districts.