Storage management, especially second storage management is the physical implementation level for every database system. Persistence is nonsense without adequate support of second storage management. This paper discusses three approaches for integrating programming language and persistent objects firstly, then introduces the design of storage management subsystem (SMS) of MIDS/BUAA, i. e. (1 ) the architecture of SMS, (2) storage structure of MIDS Object, (3) object identity design, (4) objects clustering and indexing, (5) persistence implementation, (6) dynamic UID transformation to memory address.