Abstract: Objective To explore the relationship between personality traits and well-being among breast cancer patients and to provide basis to improve the quality of life of breast cancer patients. Methods A total of 180 breast cancer patients and 180 healthy female cotrols were selected at Affiliated Tumor Hospital and Physical Examination Center of Harbin Medical University in October 2011 for a questionnaire survey with Big Five Personality Inventory and a happiness index scale to evaluate the personality characteristics and the happiness index of the subjects. Results The Big Five personality scores of adaptability and sense of morality of the cancer patients were 46.52±12.31 and 56.51±6.67 and significantly higher than those of the controls(42.70±10.76 and 44.72±8.53;P<0.05);the scores of sociability, openness of the patients were 54.78±9.31,43.49±11.22 and obviously lower than those of the controls(62.24±9.28, 60.08±11.76;P<0.05).Breast cancer patients had a happiness index score of 9.35±2.47,significantly lower than that of the controls(12.82±1.46;P<0.05).Openness,altruism and happiness index were positively correlated among breast cancer patients(r=0.232,P<0.05;r=0.256,P<0.05). Conclusion Personality traits is one of the factors that affect the well-being of breast cancer patients.