Cultural heritage is divided into artificial cultural landscapes and natural environments. In the rapid urbanization process, Chinese heritage is confronted with pluralistic thoughts, among which a critical perspective emphasizes the coupling of cultural landscapes and natural environments. In the practices of heritage preservation, excessive human intervention leads to the destruction of authenticity, while insufficient intervention results in inefficient protection. At the current urban development stage of improving the quality of existing stock, China urgently needs resilient and sustainable design ideas to guide heritage preservation. So that the city can establish a Third Landscape system for cultural heritage protection during its development. The Third Landscape theory was brought up by French landscape architect Gilles Clément, which is made up of all the marginal places neglected by human beings that assemblage a rich biological diversity not yet been classified. This paper combines the Third Landscape theory with heritage preservation. By analyzing the ecological value, age value, and aesthetic value brought by the Third landscape during heritage preservation, and combining the case study of the Third Landscape Garden in France and the Old Town of Edinburgh in England. The study explores and reflects on the predicament and problems of current Chinese heritage preservation with the concept of the Third Landscape theory. At the urban scale, the Third Landscape can effectively preserve the original urban texture. At the block scale, various types of neglected spaces meet the conditions for developing the Third Landscape. By taking historical heritages as nodes and organizing these leftover spaces together, an integrated ecological corridor can be formed between heritages and numerous fragmented spaces, thereby bringing an aesthetic continuity. At the architectural scale, the utilization of the Third Landscape can enhance the plasticity of the spatial imagery of heritage while maintaining its authenticity. Therefore, the preservation approach of the Third Landscape is characterized by flexible intervention, high reversibility, and low cost. At the same time, by combining heritage preservation with urban renewal, it transforms the heritage from isolated islands under protection into an archipelago actively connecting with the outside, forming a continuous ecological network. The combination of the Third Landscape and heritage conservation not only activates fragmented residual land but also resists the negative impacts brought by capital in the rapid urbanization process, thereby enhancing the potential influence of the integration of authenticity and traditional imagery on urban aesthetics.