Abstract: Objective To explore the characteristics of obesity index and their internal consistency among adults aged 20-69 years in Liaoning province.Methods Data on a total of 5817 adults in Liaoning province were extracted from the dataset of third wave of China's national physical fitness surveillance.Gender and age specific distributions of waist-to-height ratio(WHtR),waist circumference(WC),waist-to-hip ratio(WHR),and body mass index(BMI) were analyzed.Results In the male adults,WHtR,WC,and BMI increased with age and then decreased in those aged 60-69 years;in the female adults,WHtR,WC,WHR,and BMI increased with age and reached the highest levels in those aged 60-69 years.The internal consistency between BMI and WHtR,BMI and WC was moderate,and decreased with age,with the kappa values decreasing from 0.63-0.68 for the adults aged 20-29 to 0.48-0.51 for the adults aged 60-69 years.Misclassification rate of central obesity based on BMI increased with age;for the 60-69 years old adults with normal BMI,35.7% (51/143) of the males and 54.9% (73/133) of the females were central obesity categorized by WHtR and 26.6% (38/143) of the males and 42.9% (57/133) of the females were central obesity defined by WC.Conclusion Distributions of obesity indexes in adults changes with age.BMI combined with either WHtR or WC can improve the efficiency for the identification of obesity,which is particularly important for the adults aged 60 years or older.