Abstract: Objective To explore the effect of social network on Alzhemier's disease(AD)among the elderly.Methods The data were collected from a cross sectional study conducted in a community population of Guiyang city.A case control study was made to analyze the effect of social network on AD.Data analysis was conducted with χ² test and non-conditional logistic regression.Results After adjusting for age and education,old people who met their children more than once a week had a lower risk of AD(OR=0.26,95%CI=0.07-0.94).Significantly lower risk of AD was existed in the elderly living with others(OR=0.37,95%CI=0.18-0.76).Compared with a poor social network,an extensive social newtork led to the lowest risk of AD among the elderly(OR=0.06,95%CI=0.007-0.60).Conclusion There is a close association between social network and AD.An extensive social network may be heplful to prevent AD.