Objective To explore the association of mild cognitive impairment (MCI) with obesity level in middle and elderly population. Methods A total of 19181 subjects aged 50-85 years were collected in this study from the first and second recruitment phase of the Guangzhou Biobank Cohort Study. The subjects received face-to-face interviews to collect the detailed information on their sociodemographic background, occupational exposures, living environment, lifestyle, family and personal disease histories, and had physical examinations and tests including 12-lead ECG, chest radiograph, and pulmonary function testing. Each subject was screened for a range of fasting biochemical parameters. The cognitive ability was tested with 10-words delayed memory test. The associations between cognition function and anthropometric indices of obesity, including body mass index, waist-to-hip ratio (WHR) and waistline, were evaluated. Results Apart from fast glucose and hypertension in subjects with normal cognition function and abnormal cognition function, some lifestyle and such physiological and biochemical factors as age, education, smoking status, and drinking status were significantly different in both gender (P＜0.05). WHR was the independent risk factor of MCI in both gender (P＜0.05). Logistic regression indicated that high WHR was a risk of MCI in both gender; the greater the WHR, the poorer memory the middle and elderly population; the OR and 95％ CI was 1.57 (1.42-1.72) in female and 1.22(1.05-1.41) in male. Conclusion Centripetal obesity is associated with MCI. WHR is a sensitive indicator influencing the cognitive function in women.