Abstract: Objective To explore the association between the clustering of premature,parity,maternal hypertension,birth sex and low birth in Linxia county,Gansu province.Methods With cluster random sampling,3 195 infants and their parents were selected from 6 towns of Linxia county from Jan 2006 to Dec 2008 for a face to face interview using a self designed questionnaire.Results After adjusting for region and nation,the odds ratios(95% confidence intervalCI)of low birth weight associated with the clustering of premature,parity,maternal hyper tension,birth sex were 1.919(95%CI:1.268-2.904),5.333(95%CI:3.391-8.387),and 5.706(95%CI:2.025-16.08),respectively,compared with non existence of the risk factor.Oddsratios of the clustering of two risk factors or more were all more than that of one risk factor.Conclusion The risk of low birth weight is increased with the number of clustering of risk factors among the infants in Linxia county.