Objective To investigate the level and determinants of decisional conflict in young and middle aged breast cancer patients to make decision for breast cancer surgery. Methods A total of 198 young and middle aged breast cancer patients to receive surgical management were investigated using a self-designed general information questionnaire, the Decisional Conflict Scale （DCS） and Perceived Social Support Scale （PSSS）. Results The sample scored （43.59±15.68） points in decisional conflict. Multiple stepwise regression analysis showed that family support and other support in the PSSS, average monthly household income, age, educational attainment, and disease knowledge were predictors of decisional conflict in young and middle aged breast cancer patients （adjusted R2=0.783, P＜0.05，P<0.01）. Conclusion Young and middle aged breast cancer patients reported severe decisional conflict in surgical choice. It is suggested to improve social support for patients from the perspective of family and work relationships, and provide consultation for those who are young, who have lower educational level and poor disease knowledge level, thus to reduce their decisional conflict.