Abstract: Urban greening construction is an important way to protect and promote urban biodiversity. However, homogenization of species biodiversity for landscape woody plants is a brake on the maintenance of urban biodiversity. Therefore, in this study, landscape woody plants in China’s 36 major cities were divided into four types according to the different geographical origins, namely native species, extra-province species, alien species, and cultivated species. We explored the landscape plants’ homogenization characteristics under national and climatic scales to clarify different characteristics under different geographical scales. We also revealed the main species that lead to the homogenization of landscape plants under different geographical scales. We found that the landscape plants’ homogenization exhibited scale-dependent phenomenon under the national scale, predominantly caused by cultivated and alien species. Under climatic scale, landscape plants in the northern subtropical zone had the highest homogenization degree of species composition, followed by middle subtropical and warm temperate zones, and southern subtropical and middle temperate zones with the lowest ones. Moreover, despite cultivated and alien species caused a tremendous impact on homogenization under climatic scale, native and extra-province species also contributed to it to certain degrees. In summary, this study can provide a basis for formulating universal solutions to alleviate landscape plants’ homogenization in China, so as to protect and promote urban biodiversity.