The characteristic of quality information management in multi-specification & small-batch was discussed, compared with mass production. Quality BOM was defined and its specific contents were described. On this basis, quality information modeling method based on quality BOM was introduced. The information model of quality structure tree was established and information structure of quality node was described in detail. Three different methods of quality defects relevance, including weak relevance method, strong relevance method and black box relevance method, were introduced, which satisfied different requirements of quality capacity evaluation. Functional models of Nimak Quality Information Management System were introduced as an application example. It was proved by this application example that the research provided a new solution to the problems of quality information management.