Abstract: Objective To investigate the influencing factors of simple obesity among preschool children in Zhengzhou and to provide evidence for obesity intervention.Methods A total of 4328 preschool children from 18 kindergartens were selected by cluster sampling method,and their heights and weights were measured and evaluated. Simple obesity children detected by body examination were matched with normal children at the ratio of 1:2 for a case-control study. All parents both in the obesity group and the control group received a survey about influencing factors on obesity.Results Multi-factors conditional logistic regression showed that birth weight ≥4.0 kg(OR=2.253, 95%CI:1.249-4.063, P=0.007), strong appetite(OR=4.251, 95%CI:2.889-6.253, P<0.001),eating fast(OR=4.638, 95%CI:2.869-7.495, P<0.001) were associated with obesity in this study.Conclusion Birth weight and eating habits are related to obesity for 3-6 years old children in Zhengzhou.