Abstract: In this paper, granularity transformations based on a new CDFG format intended to support granularity selection in Hardware/Software partitioning are proposed. The transformations comprise the merge and expand operations, and use the hierarchical node as the transform bridge. Some requirements on the transformations are presented to maintain the syntax and semantics coherence of the system. The analysis shows that the proposed transformations are efficient, persistent and easy to implement. These features are suitable for the granularity selection in the Hardware-Software partitioning.