Objective To investigate cognitive function among patients undergoing hematopoietic stem cell transplantation, and to analyze its influencing factors, so as to provide reference for early recognition and intervention in clinic. Methods A total of 152 patients undergoing hematopoietic stem cell transplantation were investigated using the Chinese version of the Functional Assessment of Cancer Therapy-Cognitive Function Instrument （FACT-Cog）, Functional Assessment of Chronic Illness Therapy-Fatigue Instrument （FACIT-F）, Hospital Anxiety and Depression Scale （HADS）. Results The total score of cognitive function among the patients was （120.57±21.32）. Regression analysis indicated that, gender, age and fatigue were the main influencing factors of cognitive function （P＜0.05,P＜0.01）, which explained 37.3% of the total variance. Conclusion Patients undergoing hematopoietic stem cell transplantation are in the risk of cognitive impairment, and gender, age and fatigue are its major influencing factors.Me-dical staff should pay attention to the patients′ cognitive status, implement targeted intervention according to their cognitive impairment, so as to prevent and alleviate their cognitive dysfunction.