Objectives:To examine the efficacy of an intervention based on the theory of planned behavior (TPB) in improving breastfeeding behavior among women with cesarean sections (C-sections).Methods:This research was a randomized controlled trial.Women with planned elective C-sections were recruited to participate in a randomized controlled trial between June and September 2020.One hundred thirty-two women were divided randomly into the intervention (n-66) and control group (n =66) by systematic random sampling.In the intervention group,an intervention project was implemented after the C-section to establish positive breastfeeding attitudes,cultivate supportive subjective norms,enhance perceived behavioral control,and strengthen breastfeeding intention to change behaviors.Those in the control group received routine pre-and post-delivery care.Exclusive breastfeeding rate and breast problem were collected at 5 days,2 weeks,and 1 month after C-section.The modified Breast-feeding Attrition Prediction Tool (BAPT) on the first day in the hospital,two weeks,and one month after C-section and Numerical Rating Scale (NRS) 24 h postoperatively were used to compare the intervention effect between the two groups.Results:After the intervention,the intervention group had significantly higher exclusive breastfeeding rates than the control group at five days (86.4％ vs.60.6％),two weeks (77.3％ vs.57.6％),and one month(74.2％ vs.50.0％) after the C-section.Besides,the intervention group was less likely to have sore nipples at five days (6.1％ vs.18.2％ in the control group,P ＜ 0.05) and two weeks (9.1％ vs.12.1％ in the control group,P ＜ 0.05).After two weeks of intervention,attitude scores (90.64 ± 8.31 vs.87.20 ± 8.15,P ＜ 0.05),subjective norm scores (88.07 ± 24.65 vs.79.42 ± 19.47,P ＜ 0.05) and behavior control scores in the intervention group were significantly higher than those in the control group.After one month of intervention,attitude scores (90.34 _± 10.35 vs.84.22 ± 10.51,P ＜ 0.05) and behavior control scores(43.13 ± 5.02 vs.39.15 ± 4.69,P ＜ 0.05) in the intervention group were significantly higher than those in the control group,which resulted in the higher breastfeeding intention in the intervention group.Conclusion:This study indicated that the TPB-based interventions effectively improved women's breastfeeding behaviors after C-sections.