In this paper, a method is proposed to develop a concurrent program from a VDM－SL (Vienna development method-specification language) specification. On the basis of DD-VDM (data decomposition-Vienna development method), service parallelism, internal parallelism and virtual atomicity can be observed in the development process. Then a nested object-oriented structure is presented to specify these parallelisms. This nested structure can be implemented with several language structures for two different kinds of applications including share-variables parallel system and distributed parallel system.