OBJECTIVE The preoperative poor nutrition of children with congenital heart disease (CHD) impacts the postoperative rehabilitation process of pediatric CHD cases. The factors of these children's preoperative poor nutrition, excluding the disease, have been underreported. The aim was to investigate the preoperative nutritional status of children with CHD who required a simple surgical repair and to analyze the maternal characteristics that are associated with poor nutrition in these sick children. METHODS This was a cross-sectional survey. The weight and height of the children were measured, maternal data were collected via a questionnaire and a univariate analysis and multivariate logistic regression were used to analyze the association between maternal factors and the preoperative poor nutrition of the children with CHD. RESULTS A total of 119 children with simple CHD were recruited to the study. The prevalence of poor nutrition was higher in the children with CHD ("cases") than in the healthy children ("controls"). An increased risk of poor nutrition was associated with lower mothers' perception, education level, understanding of the disease, and higher anxiety. CONCLUSIONS Paying attention to maternal anxiety, depression, and knowledge and providing interventions for the mothers of children with CHD are important in order to promote the nutritional status of these children.