Objective:To study the effect of a three-in-one counseling model on mental health of medical students Method: A three-in-one counseling model composed of mental health education, group counseling and individual counseling was applied to 150 freshmen of a medical school (study group) Other 150 freshmen were collected as control The intervention lasted for 1 year The effect was assessed with EPQ, SCL-90, GWB (gross well being), SCCS (self-consistency and congruence scale), SAD (social avoidance and distress scale) and LESU (life events scale of undergraduates) at the baseline, in the middle and at the end of the study Result: After intervention, the study group had lower score in psychoticism of EPQ (46 3?7 5) than control group (50 7?11 9), and higher score in flexibility (48 9?5 6) than control (46 8?5 9) The total score and many subscores of SCL-90 decreased in study group While the scores of social avoidance and distress increased in control group Conclusion: The three-in-one counseling model has effect on balancing personality, reducing psychosomatic symptoms, facilitating self consistency and improving social interaction of medical students