The paper has analyzed decorative characteristics and architectural style of Leichang Former Residence which have been summarized as precise axial space sequence that can be divided into dragon gate, central room and drawing room. It has explained the spatial-temporal view of "the unity between heaven and human" and human’s subjective ideological connotation in Leichang Former Residence. From the perspectives of the spiritual connotation of roof decorations, grading system of roofing tiles and manifestation form, it has deeply revealed the important expressive force and representativeness of roofs in architectural group, pointed out its aesthetic feature and spiritual restriction to architectures even human’s behavior, and showed that the roof is the architectural factor directly manifesting "rituality" and "the unity between human and heaven" in Chinese traditional culture.