Objective To develop the psychological intervention to promote illness acceptance for breast cancer patients,and evaluate its feasibility and preliminary effectiveness. Methods The psychological intervention was developed by means of literature review,descriptive study,related theories and experts’ consultation. And the expert’s demonstration and revision were carried out. The Acceptance and Commitment therapy-based psychological intervention were formed,including 4 modules:living with it;mindful life;accepting it;developing with it. Each module lasted 60 to 70 min. The intervention was carried out in one group. The feasibility was accessed and the Hospital Anxiety and Depression Scale,Acceptance and Action Questionnaire Ⅱ,the Illness Cognition Questionnaire,Functional Assessment of Cancer Therapy-Breast,and Perceived Social Support Scale were used to evaluate the effectiveness. Results For the feasibility study,the recruitment rate was 65%,the retention rate was 82%,the adherence rate for homework were from 50% to 64%,and the acceptability rate was 100%. The score of acceptance of illness,psychological flexibility,quality of life and perceived social support were statistically increased pre-to post-intervention(P<0.05). The score of Acceptance and Action Questionnaire Ⅱ was statistically decreased pre-to post-intervention (P<0.05). Conclusion This psychological intervention for illness acceptance was scientific and systematic,and it was feasible among breast cancer patients during their treatment period.