It is an efficient way to use SDG (system dependence graph) in slicing object-oriented program. But SDG is too complicated, so it may produce mistakes during constructing SDG, which will lead to inaccurate result. In this paper, the SSDG (simplified system dependence graph) is presented, which ignores nodes and edges representing parameter-in or parameter-out and summary edges. Meanwhile, the concept of coarse-grained slice for object-oriented program is defined, its properties are discussed, the relationships between coarse-grained slice and fine-grained slice are analyzed, the object-oriented coarse-grained program slice is computed based on simplified system dependence graph, and the implementation is also discussed.