Objective: to understand the present situation of job burnout among medical interns and to explore its major influencing factors. Methods: A stratified random sampling was used to select 1268 medical interns from 6 full-time medical colleges in Guangdong province. They were investigated with Maslach Burnout Inventor-General Survey, (MBI–GS), Questionnaire on Humanistic Care Ability of Medical Students (QHCAMS) and a self-compiled personal information questionnaire. Results: (1) The incidence of job burnout in this group was 98.40%. The total score of MBI–GS and the scores of emotional exhaustion, cynicism and reduced personal accomplishment were (45.27 ±12.61), (16.21 ±4.91), (12.91 ±3.93) and (18.15 ±5.22), respectively. (2) The result of multiple stepwise linear regression showed that gender, specialty, type of internship hospital, working department and average length of overtime per day were positively correlated with the total score of MBI-GS (β =.154~.676, all P < 0.01). Nine factors, such as self-evaluation of health status, ability to solve problems at work, relationship with patients, classmates and medical staff, as well as the scores of hope, honesty, humility and courage in HQCAMS, were negatively correlated with the total score of MBI-GS (β =-.148~-.468, all P < 0.01). Conclusion: Medical interns are suffering serious job burnouts, which may be related to work pressure, personal quality and other factors.