This study mainly investigated the mediating effect and the moderating effect of career competencies in the Job Demands-Resources Model. Career competencies are a kind of knowledge accumulation, including knowing-why, knowing-how and knowing-whom, which could influence employees’ career. The basic assumption of the Job Demands-Resources Model is that every work environment is characterized by occupation-specific job resources and job demands, and it includes two processes for the development of burnout. First, long-term excessive job demands from which employees do not adequately recover may lead to sustained activation and overtaxing, eventually resulting in exhaustion; second, job resources lead to increased levels of motivation in the form of work engagement (Demerouti, Bakker, Nachreiner, & Schaufeli, 2001). Previous studies has shown that personal resources may act as a mediator in motivational process, and can stimulate employees’ work engagements (Xanthopoulou, Bakker, Demerouti, & Schaufeli, 2007), and may also act as a moderator in health impairment process, and can reduce burnout. Career competencies may be expected to act in a similar way as personal resources in stimulating employees work engagements and reducing emotional exhaustion in the Job Demands-Resources Model (Akkermans, Schaufeli, Brenninkmeijer, & Blonk, 2013). Based on the Job Demands-Resources Model and conservation of resources theory, our focus is to investigate the mediating effect and the moderating effect of career competencies in the Job Demands-Resources Model. 201 employed persons were measured with the professional competence measurement scale, the questionnaire of career development, the Job Content questionnaire, the Questionnaire on the experience and assessment of work, the MBI - GS Scale and the Utrecht Work Engagement Scale. Mplus and SPSS were used to analyze the data. The results showed that: (1) Job demands statistically significantly affected emotional exhaustion(r=0.16, p<0.05); and career competencies acted a moderator on the relationship between job demands and emotional exhaustion(β=-0.49，p<0.01; △R2=0.03)，and the relationship between job demands and emotional exhaustion were weaker for employees in high career competencies condition than in low career competencies condition. We used the Johnson-Neyman’s method to test the simple slopes, the result showed that when the mean-centered moderator M (career competencies) in [-2.18, 0.45], simple slope a+cM=.65-.49M were significant.(2) career competencies significantly affected work engagement; (3) Career competencies acted a mediator on the relationship between job resources and work engagement(c=0.48, p<0.001; a=0.56, p<0.001; b=0.30, p<0.001; c’=0.31, p<0.001). In summary, Career competencies are shapeable abilities, and it is important and useful for employees to promote their work engagements, and then to achieve their career goals. Studies of Career competencies in the eastern culture are still in its infancy. With putting more attentions on career competencies, HR programs may benefit from this insight by simultaneously increasing job resources and career competencies to increase employee engagement and reduce their exhaustion. On the one hand, HR program should provide the sufficient job resources to employees, such as social support, opportunities of development and autonomy, and job demands should be controlled within a certain range to avoid exhaustion. On the other hand, HR program should use some relevant career management measures to strengthen employees’ career competencies, such as the career management skills training courses.