Objective To understand the awareness of childhood obesity and its related disease in parents from Gaohang town,Shanghai. Methods A cross-sectional study was performed in five schools in Gaohang town in 2013.Physical examination and liver ultrasoundgraphy were made for 2 047 students entered this study.Furthermore,a self-completed questionnaire was also made in parents. Results The rank of well known diseases related with childhood obesity were non-alcoholic fatty liver disease(NAFLD),high blood pressure,precocious puberty,abnormal blood glucose,obstructive sleep apnea-hypopnea syndrome (OSAHS),joint pain respectively in the views of parents.And the reasons for childhood obesity were unreasonable diet,less exercise,genetic factors,other disease,psychological factors respectively in the view of parents.According to the survey,more than half of 595 overweight children's parents underestimated the children's weight status.Binary Logistic regression analysis showed that parents of overweight children were more prone to underestimate the weight compared with the obese children's parents(OR=5.44,95%CI:3.75~7.90,P<0.001).Likewise,it was similar Results when compared parents whose children without obesity related diseases with parents whose children with obesity related diseases(OR=2.03,95%CI:1.40~2.97,P<0.001).Interestingly,parents without chronic diseases were easier to wrongly estimate their children's weight status compared to parents with chronic diseases(95%CI:1.20~7.90,P=0.004). Conclusions The parents are lack of the knowledge related with childhood obesity.They are prone to underestimate the weight status of the overweight or obese children.