Abstract: ObjectiveTo explore the relationship between type A personality,defense style and suicidal ideation among undergraduates.MethodsTotally 406 undergraduates in Jiangxi province were investigated with Self-rating Idea of Suicide Scale(SIOSS),Type A Behavior Pattern Scale and Defense Style Questionnaire(DSQ).ResultsOf the undergraduates investigated,11.8% had suicidal ideation.The ratio of type A personality for the student reporting suicidal ideation was 54.2%,which was significantly higher than that of students without suicidal ideation(19.0%).Compared with those of the students without suicidal ideation,the students with suicidal ideation had significantly higher scores in time hurry (15.81±3.46 vs 11.72±3.56),competitive hostility(13.65±3.09 vs 11.83±3.40),total scoce of type A personality (29.46±5.63 vs 23.54±6.03),immature defence style(4.91±1.00 vs 3.80±0.76),and intermediate defence style (4.66±0.53 vs 4.43±0.60),but lower score in the mature defense style(P<0.05 for all).ConclusionType A personality and defense style have significant influences on suicidal ideation among undergraduates.