Abstract: Based on 321 samples from college graduates, this paper investigates the relationship between social support and job-search behavior. Career decision-making self-efficacy(CDMSE) is introduced to construct a mediation model. In addition, the study also creatively introduces proactive personality and social capital to verify their moderating effects in this model. Results show that the relationship between social support and job-search behavior is partially intermediated by CDMSE. This study also indicates that high proactive personality weakens the association between social support and CDMSE. Besides, one's proactive personality and perceived social support play alternative role in the job search process. What's more, social capital is found to play a negative moderating role on the relationship between CDMSE and job search behavior. With the strengthening of social capital, the impact CDMSE has on job search behavior gradually weakens. According to the results, it is concluded that the individual internal proactive personality and external social capital play important roles in the process of job search, and it is reminded that college students should develop themselves comprehensively which has a certain guiding significance for them.