Abstract： Objectives To develop a measurement for obesity assessment which could be used as a simple tool of risk screening. Methods The data of National Nutrition and Health Survey ( 2002 ) were used to analyze the relationship between body mass index ( BMI ), waist circumference (WC) and chronic diseases, based on which chronic disease index ( CRI ) was established. Receiver operating characteristic curve (ROC) was used to determine the cut-off of CRI and to compare the predictive effectiveness of CRI,BMI and WC on chronic diseases. The kappa test was chosen to estimate the consistency of different cut-off of CRI with BMI and WC. The odds ratios of chronic diseases in different cut-offs of CRI were calculated by multiple Logistic regression analysis. Results CRI was calculated as CRI = BMI + 3.5 WC. In ROC curve,the cut-off of CRI was 300. The predictive effectiveness of CRI was higher than that of BMI and WC. CRI at 300 showed the best consistency with 24 kg/m2 BMI and 85 cm WC (P <0. 05 ). In comparison with CRI <300,the risk of chronic diseases was significantly increased with an increase of 20 U CRI. Conclusion CRI shows good predietive effectiveness and could be used to identify those with higher risk of chronic diseases.