Objective To explore the mental health status of patients with breast cancer and social support on their influence. Methods 260 cases of patient with breast cancer were investigated by using the questionnaire of demographic characteristics and symptom check list 90 (SCL-90) and social support rating scale (SSRS). Results Breast cancer patients ' mental health condition was worse than normal healthy people and their mood changes were obviously observed. Breast cancer patients achieved good social support.However, the urban patients with breast cancer got better social support than the rural patients and the difference were statistically significant (t =7.91, P =0.000). SCL-90 total score and its factors such as forced symptoms, sensitive interpersonal relationship, depression, anxiety, hostile, terror, paranoid,psychoticism,were negatively related with the social support (r =-0.278,-0.259,-0.165,-0.294,-0.215,-0.177,-0.175,-0.167,-0.219,all P ＜ 0.05).Conclusion The social support influences breast cancer patients' mental health,therefore,the patients with breast cancer should be given a better social support in order to improve the psychological health level and improve recovery.