Abstract: The research tests the students， subjective wellbeing of Jiangnan University in different grades and different specialized fields by the Index of Well-being, mainly studies the effects of demographic factors on college students，subjective well-being. The results demonstrate as following： the subjective well-being of college students exist obvious difference in different grades and different sexes, the factors such as specialized fields, source area, only child or not, parents education level and pin money, have a less influence on the subjective well-being of college students.