<b><i>Background:</i></b> Childhood overweight and obesity have become some of the most serious public health problems in the 21st century and have a significant impact on affected children as they grow into adulthood. <b><i>Objective:</i></b> The purpose of this study was to evaluate the overweight and obesity status and their main influencing factors in preschool children aged 2–7 years in urban areas of China between 2011 and 2017. <b><i>Methods:</i></b> A stratified cluster random sampling method was used to conduct a sample survey of children aged 2–7 years in Xiamen, one of China’s five special economic zones. The 56,738 participants (29,444 boys, 27,294 girls) were examined at three time points (15,757 in 2011, 19,098 in 2014, and 21,883 in 2017), and were analyzed for factors influencing obesity. <b><i>Results:</i></b> Between 2011 and 2017, the prevalence of overweight and obesity in preschool children between 2 and 7 years old was 10.91 and 5.66%, respectively. The overweight and obesity rates were higher in boys (11.85 and 7.11%) than in girls (9.90 and 4.09%), and the difference was statistically significant (<i>p</i> &#x3c; 0.01). In the past 7 years, the overweight and obesity rates showed a downward trend in both boys and girls (<i>p</i> &#x3c; 0.01). The peak ages for overweight were 6 years in boys and 2 years in girls, while the obesity rate peaked at 6 years. In those children with obesity, the proportion of those with moderate to severe obesity decreased from 40.70% in 2011 to 32.80% in 2017. Multiple stepwise regression analysis showed that children who were averse to sports activities preferred greasy foods and had earlier introduction of solid foods as infants, as well as those who were born at a high birth weight, ate fast, and those with parents with obesity were more likely to have obesity themselves (<i>p</i> &#x3c; 0.05). <b><i>Conclusions:</i></b> Although preventative and control measures for childhood obesity have achieved initial results, Chinese preschool children remain to have high levels of overweight and obesity. It is therefore necessary to strengthen monitoring of overweight and obesity in preschool-aged children and implement appropriate interventions when necessary.