Objectives: The aim of this study was to examine several factors related to low self-esteem among obese Chinese primary-school students. Methods: A cross-sectional study was conducted between June 2009 and June 2010. A total of 1,410 primary-school students (China grades 4 - 6) in Changsha city were divided into normal weight (n = 1,084), overweight (n = 211), and obese groups (n = 115) according to world health organization (WHO) growth standards for body mass index (BMI). The students were assessed using the self-esteem scale (SES) and a general situation questionnaire. Caregivers completed questionnaires about their child's weight status. Self-esteem levels were explored; any factors related to low self-esteem were analyzed using logistic regression analysis. Results: The average self-esteem score among overweight or obese primary-school students was found to be lower than that of normal-weight students. The proportion of students with low self-esteem in the obese group was more than that in the normal-weight and overweight groups. Multiple logistic regression analysis showed that obesity status (odds ratio [OR], 3.74; 95% confidence interval [CI], 2.25 - 6.22), overweight status(OR, 2.60; 95% CI, 1.71 - 3.95), obesity considered by children's grandparents(OR, 1.76; 95% CI, 1.05 - 2.96), dissatisfaction with height (OR, 1.55; 95% CI, 1.11 - 2.18), and dissatisfaction with weight (OR, 1.45; 95% CI, 1.05 - 2.01) were the risk factors for low self-esteem for primary-school students, while satisfaction with academic performance was a protective factor (OR, 0.22; 95% CI, 0.07 - 0.71). Conclusions: For Chinese primary-school students, low self-esteem is associated with higher weight status and self-perceived body shape and academic performance. In addition, grand parental opinion of a child's weight also contributes to low self-esteem.