Bill Of Material (BOM) is the most important data for modern manufacturing enterprises. To satisfy different requirements in various departments, BOM is modeled in kinds of ways. Meanwhile, how to transfer BOM between departments become troublesome. As a ideal method, integrated BOM model is out of reach for lacking effective approach. This paper proposes a layered BOM model to integrate multi view into a whole one. Furthermore, colored digraph is applied to represent the layered model in mathematic. Also a BOM case is given to verify the method proposed.