Objective To investigate the situation and influencing factors of the breastfeeding selfefficacy among primiparas in order to provide evidence for intervention of breastfeeding promotion.Methods Totals of 382 primiparas were recruited and investigated by convenience sampling method between November 2010 and November 2011 with questionnaires such as breastfeeding confidence scale and social support scale.Results The average scores of breastfeeding self-efficacy among primiparas was (102.86 ±15.29).The primiparas with different ages (20 ～ 24,25 ～ 29,≥ 30 years),period of maternity leave (＜ 2,2 ～3,＞ 3 months),breastfeeding education before ante partum had significantly different score of breastfeeding self-efficacy (P ＜ 0.05).The influencing factors of self-efficacy included age,period of maternity leave,breastfeeding education before ante partum.The dimensions of emotion support,information support and evaluation support of social support were positively correlated with the total score of breastfeeding self-efficacy (P ＜ 0.05).Conclusions Breastfeeding education for the primiparas should be strengthened to promote breastfeeding behaviors.Further more,the primiparas' individual and social backgrounds should be considered during the education.