According to theory of social exchange and border theory, based on the survey questionnaires from 263 female knowledge workers, the mediating effect of work-family balance in the relationship between family supportive supervisor behavior (FSSB) and affective commitment is examined, and the moderating effect of boundary flexibility-willingness is tested. Results from hierarchical regression analysis and bootstrap analysis indicated that: FSSB has a significant positive effect on affective commitment; work family facilitation plays a mediated role between FSSB and affective commitment; the mediating effect of work family facilitation between FSSB and affective commitment is stronger under the condition of high boundary flexibility-willingness. The research conclusions provide useful implications for enterprises to retain female knowledge workers and play their roles effectively.