In this paper, a scheme for extending traditional system dependence graph based on object orientation is presented, i.e., an object-oriented system dependence graph (OOSDG) suitable for object-oriented program is constructed by combining SDG with ClDS (class dependence subgraph) and CHS (class hierarchy subgraph). The extension of syntax and semantics and function of SDG are discussed. Meanwhile, the algorithm for constructing OOSDG is provided, and application aspect is also analyzed.