Abstract: ObjectiveTo evaluate the social support state of undergraduates and to discuss the effects of social support on suicidal ideation.Methods753 undergraduates of Ji'nan university were selected with stratified random cluster sampling method and investigated with the questionnaires.ResultsWe found that the main sources of social support of undergraduates were from family members,friends,classmates,lovers and relatives.When confronting difficulties,only and 19.7% of the undergraduates would tell others actively.19.9% of them would actively ask for help.The score for subjective support,the utilizations of the social support and the total score of the suicidal ideation group were lower than those of the non-suicidal ideation group,and the difference was of statistical significance(P<0.01).ConclusionThe social support and its utilizations of undergraduates have impact on suicidal ideation.Related measures should be taken to strengthen the social support and improve the undergraduates'ability to seek social support in order to prevent suicidal ideation and suicidal behavior.