In this paper, a new feature-based assembly library for injection mould bases is presented. Assembly design feature-object modeling and configuration management are the key technologies developed. This library is an important functional module of QuickMould, which is a productivity software tool for plastic injection mould design. Interactions between the library and mould design processes are realized. This paper also covers the details about the design of the system and the realization of some major functions, with which, the process of traditional mould design is simplified and standardized. Consequently, the lead-time for plastic injection mould can be significantly shortened.