Abstract: To explore the mediating effect of gratitude between the existential anxiety and the life satisfaction. 717 undergraduates were investigated with the College Students' Existential Anxiety Scale, the Revised College Students Gratitude Questionnaire, the Life Satisfaction Scales Applicable To College Students. The existential anxiety was significantly negatively correlated to gratitude and life satisfaction, while gratitude was significantly and positively correlated to life satisfaction. Stepwise regression analysis showed that gratitude played a partly mediating role between existential anxiety and life satisfaction with the total effect reaching 16.3%. The different levels of existential anxiety could directly effect on satisfaction with life, and can also effect on life satisfaction through gratitude.