Objective To analyze the main factors of simple obesity in preschool children,and to give some effective measures. Methods Health questionnaires were handed out to 452 four-year-old preschool children from three different kindergartens and some interventions were conducted in May 2015.The effects of these interventions on overweight/obesity and body mass index (BMI) of preschool children were analyzed. Results The percentage of overweight/obesity children in the experimental group decreased after one year (14.16%) and the difference had no statistical significance(χ²=0.43,P＞0.05) while the percentage of overweight/obesity in children of observation group showed sharp increase (16.37%) and the difference was statistical significant(χ²=4.82,P＞0.05).Meanwhile,the research indicated that the main factors were mothers with overweight/obesity,children taking in too much meat (over 30%),overeating,and eating too fast,as well as shortage of sports.After intervention,the trend of BMI of overweight and obesity in children showed gentle increase(t=2.30 and 2.27,P<0.05),the curve of overweight closed to be normal. Conclusions Multiple factors result in overweight/obesity in preschool children.The trend of children overweight/obesity can be controlled by some effective interventions;However,the sustainability of intervention effects needs to be further studied.