To reduce the negative effects of family/work conflicts on job performance, more and more organizations choose flextime work arrangements, which increase the boundary flexibility. However, some organizations argue that preventing employees’ family affairs from interfering with work by building up strong boundaries between work and family and monitoring the employees closely can ensure their job performance. Based on boundary theory, this study analyzes the path of the work flexibility influencing work performance, the mediation of psychological permeability and the moderation of work creativity. After investigating, research findings indicate that work flexibility can reduce psychological permeability, and then improve job performance. Work creativity positively moderates the relationship between psychological permeability and job performance, so flextime work arrangements can reduce psychological permeability, and help to improve work performance, especially for creative staff.