Abstract: Objective To understand the BMI condition of the nuclear family in Shanghai city by a cross-sectional study,and provide suggestions for inter vention.Methods 1 060 nuclear families were selected randomly and face to face in terviews were carried out among family members and the infomation was collected by questio nnaires.Results The over weight rate among the subjects was 25.47% and the obesity rate was 4.76%;By using logistic regression analysis we found that compared with subjects who were less than 35 years old,people who were between 40 and 45 years old or who were over 45 years older were more likely to have an over high BMI,the OR were 1.258,95%CI=0.953~1.661,1.395,95%CI= 1.003~1.942,respectively;the overweight/obesity rate was lower among the subjects whose income were between 2000 Yuan and 3000 Yuan monthly;the same as people whose health score were over 68.The possible risk factors of BMI abnor mality were eating habit,age,whether eating on time,how many hours spending on TV and so on.Conclusion The BMI condition of the nuclear family members in Shanghai city was not good,so we should carry out some effective intervention a mong them to change their bad habits and promote the health condition of nuclear family.