As the core staff of modern enterprise, knowledge workers are working under tremendous stress. The long-term work stress will bring in a series of psychosomatic and behavioral reactions. If these reactions are not been effectively alleviate, job burnout will occur, psychosomatic health and job performance will be damaged. As a personal resource, psychological capital can help workers cope with work stress, and reduce the level of job burnout. Objective: Develop Knowledge Worker Work Stressor Scale with good reliability and validity, analyze the status of knowledge workers’ work stress, psychological capital and job burnout, and explore the relationship among them. Methods: According to convenience sampling principle，722 information enterprise knowledge workers in Beijing were tested by self-made Knowledge Worker Work Stress Scale, Psychological Capital Scale, Maslach Burnout Inventory-General Survey, and analyze the data with T-test, correlation analysis, hierarchical regression analysis and other statistical methods. Results and Conclusions: (1) Based on references and in-depth interview, the Knowledge Worker Work Stress Scale was developed and validated. All indicators fit the statistical standards; (2) Status study result shows: male knowledge workers’ work stress and psychological capital were higher than the female; female and unmarried knowledge workers had susceptibility of job burnout; married knowledge workers experienced the stress of challenging work higher than unmarried workers, and also had higher self-efficacy; 21-25 years old knowledge workers felt the least work-family conflict; knowledge workers' hope level increased with age; (3) Work stress predicted job burnout significantly; (4) Psychological capital partially mediated between work stressors and job burnout.