Objective: To explore the mediating role of self-esteem between positive and negativeemotions and suicidal ideation in college students. Methods: A total of 6566 college students in Ningxiawere investigated by means of general survey, SIOSS, PANAS and SES. Results: There were significantdifferences in SIOSS scores and SES scores among different sex, source, grade and satisfaction (t=-5.327,4.128, F=4.692, 103.409; p<0.05), there were significant differences in SIOSS scores among differenteducational background and family types (t=-2.583, F=11.147; p<0.05),and the scores of positive emotionand SES were negatively correlated with SIOSS scores (r=-0.508, -0.630; p<0.01). The score of negativeemotion was positively correlated with the score of Siosss (r=0.505; p<0.01), and self-esteem played a partof mediating effect between negative/positive emotion and suicidal ideation, the proportion of mediatingeffect was 47.3%/56.3%.Conclusion:College Students’ self-esteem plays an intermediary role betweenpositive and negative emotions and suicidal ideation. The higher the level of self-esteem, the more positiveemotions college students have.