Single-piece-small-batches are typical in electric cabinet company. It results in huge BOM (bill of material) data. The article analyzes the product processes in electric cabinet company and presents BOM architecture. It is consist of design BOM, parameter BOM, manufacturing BOM, purchasing BOM and cost BOM, which simplifies BOM management and storage. BOM is denoted as weight number tree. Tuples are put forward to express the tree and the structure is converted to relational database storage. It is applied to express node query and checksum algorithms with structure query language, which proves the tuples maintainability. On this basis, BOM management system is established. Enterprise applications show that a feasible plan for electric cabinet company BOM management is presented.