In accordance with the compositionality criterion and hierarchy principle of Rhetorical Structure Theory (RST), this study reframes each tree in the RST Discourse Treebank into three new dependency trees with ultimate nodes being clauses, sentences, and paragraphs, respectively, which also draw on an analogy between syntactic and discourse trees. Detailed percentages of various RST relations at the three granularity levels are examined, illuminating the discourse processes of organizing units of one granularity level into those of the next upper level and suggesting certain homogeneity and interaction across levels in the Treebank, particularly at the two upper levels. The study demonstrates the applicability of RST analysis between same-level terminal units. With unique analytical advantages, the newly constructed discourse dependency trees provide new research prospects.