Today, the issue of knowledge acquisition and sharing it in the work field, especially in knowledge-based organizations has become more important. A library is a knowledge-oriented organization and the librarians are knowledge workers in the library. So, how to encourage librarians to share their knowledge and self-learning is very important. On the one hand, surveys show that designing work has enormous impact on the organization environment and on the other hand on sharing of knowledge among employees. This study aimed to analyze multilevel impact of job characteristics on knowledge sharing with the mediating role of organizational identification. The current survey is an applied study from the perspective of its objectives and from the viewpoint of data collection can be considered as a descriptive-survey study. Statistical population of the research is all of the librarians in public and academic libraries in the city of Ahwaz. Accordingly, a number of 108 librarians from 16 libraries in the city of Ahwaz were selected as a sample. The results analyzed on the individual level (librarians) showed that organizational identification has a significant and positive impact on knowledge sharing among librarians. Also motivational job characteristics have a significant and positive impact on organizational identification. The findings of multilevel model showed that the variable of group’s level social job characteristics has moderating effect between levels in relationship between the organizational identification and knowledge sharing and the moderating role of social job characteristics in the relationship between motivational job characteristics and organizational identification was rejected.