In China, migrant workers as low income people enter the big cities for higer income since the reform and opening up, because they believe that higher income can bring more subujective well-being. Though most researches have comfirmed that income can increase subjective well-being, especially for low income people, there is a very complicated relation between them. For example, so-called “the paradox of happiness” suggests higher subjective well-being doesn’t necessarily result from higer income. So, some mediators and moderators maybe exist between income and subjective well-being. Previous researches have found that social support and personality are two predominant influence in the causation of subjective well-being, and there is a positive association between income and social support. On the ground of the above reasoning, the current study hypothesized that: (1) migrant workers’ income would directly influence their subjective well-being; (2) Social support would mediate the association between migrant workers’ income and subjective well-being; (3) Personality would moderate the association between migrant workers’ income and subjective well-being, (4) The medating effect of social support could be modeated by personality. Based on a sample of 452 migrant workers, the present study examined the associations between income, subjective well-being, social support and personality. Hierarchical regression analyses were applied to detect the effects of income on subjective well-being as well as the mediating role of social support and the moderating role of personality in the effects of income. Results indicated that after controlling for the effects of migrant workers gender, age and education, income displayed a main effect on subjective well-being. Social support served to mediate the association between income and subjective well-being, and neuroticism, extraversion and agreeableness moderate this association in that low neuroticism, low and middle extraversion and agreeableness predicted a positive association. The mediation of social support was moderated by social identity, i.e., social support was a moderated mediator. These findings suggested that the association between migrant workers’ income and subjective well-being is non-linear and indeterminate, but for most migrant workers, income is a very important factor to increase subjective well-being, especially when they can get social support from their environment. The present study contributes to the current literature and promotes our understanding of “the paradox of happiness” from the perspective of psychology.