Objective To investigate the status of parents’ weight perception of preschool children in Luohu District, analyze the influencing factors, and to provide theoretical basis for subsequent interventions in childhood obesity.

Methods A questionnaire survey was conducted on 3 106 parents of children in 7 kindergartens in Luohu District using stratified cluster sampling. The survey contents included basic information of the children, family environmental characteristics, and parents’ perception of their children’s weight. Chi-square tests were used to compare the differences in weight perception among parents of children with different demographic characteristics. Binary multivariate logistic regression was used to analyze the influencing factors of parents’ perceived bias in children’s weight.

Results The detection rates of overweight and obesity in children aged 3 − 6 in Luohu District were 9.5% and 10.5%, respectively. Among the 3 106 parents, 36.8% underestimate their children’s weight, while 1.6% overestimate it. Binary multivariate logistic regression analysis found that being boys (OR = 1.24, 95% CI: 1.04 − 1.48), overweight (OR = 56.46, 95% CI: 31.38 − 101.56), and obesity (OR = 4.75, 95% CI: 3.67 − 6.14) were all influence factors for parents underestimating their children’s weight (all P < 0.05).

Conclusion It is common for parents to lack awareness of their children’s weight status. Parents of boys, and overweight or obese children are more likely to underestimate their children’s weight status. Health education on parents’ recognition of children’s weight should be further strengthened.