Every year, millions of university graduates in China have to face the difficult employment conditions and thus suffer great stress, so how to ease the mental tension and keep psychological well-being of university graduates during their job searching processes has attracted many researchers' attention. To seek the theoretical clues behind, this study aims to explore the predictive effects of employability, cognitive appraisal and employment insecurity on psychological well-being among university graduates during their job searching processes. Based on Self-Regulatory Theory, a research model consisted of 6 hypotheses was put up. In order to verify these hypotheses, a three-wave longitudinal survey was carried out. The wave one was conducted in October 2012, the wave two one month later and the wave three another month later. The wave one contained demographic variables and employability. Cognitive appraisal and employment insecurity were measured in the wave two. And psychological well-being was measured in the wave three. Graduates from 52 universities from 16 provinces (including municipalities) in China were invited to participate in the study, except those who were pursuing higher education or had found a job. In total, 757 valid questionnaires were gained in the wave one. In the wave two and three, 557 and 343 valid questionnaires were received respectively. The results of SEM analysis showed that: Employability predicted appraised challenge, employment insecurity and psychological well-being significantly (point est. = .216, SE = .062, BC bootstrap 95% CI = .095, .337 ; point est. = -.217, SE = .047, BC bootstrap 95% CI = -.310, -.124 ; point est. = .223, SE = .072, BC bootstrap 95% CI = .083, .364) ; Appraised challenge mediated the relationship between employability and employment insecurity (point est. = -.036, SE = .014, BC bootstrap 95% CI = -.064, -.009); The relationships between employability, appraised challenge as well as appraised threat and psychological well-being were mediated by employment insecurity (point est. = .058, SE = .024, BC bootstrap 95% CI = .011, .105 ; point est. = .057, SE = .024, BC bootstrap 95% CI = .011, .104; point est. = -.037, SE = .017, BC bootstrap 95% CI = -.071, -.004); And employability predicted psychological well-being through appraised challenge and employment insecurity sequentially (point est. = .012, SE = .006, BC bootstrap 95% CI = .000, .025); The results suggest that we should enhance graduates’ employability before or during their job searching processes, in order to help them cognize and appraise job search positively, and then release employment insecurity and keep mental health. Previous researches in China mostly concerned about the predictive effects of such variables like personality and emotional factor on psychological well-being, while this study examined the relationship of employability and psychological well-being and the mediation effects of cognitive appraisal and employment insecurity between them. Besides, this study reflected the lagged change of psychological well-being predicted by employability, cognitive appraisal and employment insecurity more convincingly using a three-wave longitudinal survey.