Objective To understand the status and difference of breastfeeding behavior in urban and rural areas of Southwest China.Methods From March to July in 2011,3659 infants aged 6-24 months were selected by stratified cluster randomized sampling method in urban and rural areas of three provinces of Southwest China (Sichuan,Yunnan and Guizhou),including 1801 (49.2％)infants from urban areas and 1858(50.8％) from rural areas.Basic information of these infants,their families and breastfeeding was obtained by a questionnaire for the mothers or baby-carers.Descriptive analysis and survival analysis (Kaplan-Meier method) were used to describe breastfeeding behavior.Chi-square test and Log-Rank test were used to identify the differences of breastfeeding behavior between urban and rural areas.Results Early breastfeeding initiation rate within one hour after birth was 10.7％(355/3315),and the numbers of urban and rural areas were 12.3％(198/1604) and 9.2％ (157/1711),respectively,x2 =8.691,P＜0.05.Totally,20.3％(725/3575) of all infants were initially fed by breast milk after delivery,and 25.1％ (440/1754) in urban areas and 15.7 ％ (285/1821) in rural areas,x2 =49.192,P＜0.05.The exclusive breastfeeding rate and breastfeeding rate within four months after birth were 35.5％ (27.4％ in urban and 43.6％ in rural areas,x2=88.678,P＜0.05)and 76.2％ (68.5％ in urban and 84.3％ in rural areas,x2 =124.702,P＜0.05),respectively.However,the exclusive breastfeeding rate and breastfeeding rate within six months after birth reduced to 11.3％ (7.9％ in urban and 14.4％ in rural areas,x22 =18.001,P＜0.05) and 65.0％ (54.0％ in urban and 76.3％ in rural areas,x2 =199.662,P＜0.05),respectively.The median breastfeeding duration was 8.0 months (7.0 months in urban and 9.0 months in rural areas,x2 =96.780,P＜ 0.05).The most common reason of weaning was insufficient breast milk which accounting for 48.7 ％ of families [56.9％ (1161/2385) in urban and 39.9％(462/1157) in rural areas,x2=68.840,P＜0.05].Conclusions In Southwest China,intervention program should be implemented to improve the breastfeeding status.Breastfeeding behaviors are different between urban and rural areas in Southwest China.The initiation of breastfeeding in urban area is better,but the sustainability of breastfeeding is better in rural area.