In this study, undergraduates’ subjective wellbeing and its relationship with personality characteristics and social support are examined by using selfreported questionnaire survey method by measuring 330 college students from 7 universities in Hainan with EPQRSC, GWBS and PSSS. The results indicate that the overall college students’ subjective wellbeing is medium and on the little higher side and that there is no significant gender difference. In four kinds of personality, sanguine college students have the highest subjective wellbeing sense while melancholy students have the lowest wellbeing sense, furthermore, social support has the same influence on subjective wellbeing sense of different kinds of college students. Correlation and regression analysis shows that nervous disposition, introverted character and extrovert as well as beyond family support have more strong influence on the subjective wellbeing sense. Nervous disposition only has direct influence on the subjective wellbeing sense but introverted character and extrovert not only have direct impact on the subjective wellbeing sense but also have indirect impact on the subjective wellbeing sense through beyond family support. 