Abstract: here have been a lot of discussions on the leisure and beautification functions and environmental designs of urban roadside green spaces, but their ecological functions, especially the biodiversity supporting services, are often overlooked. This paper analyzes the richness and similarity of bird species in roadside and surrounding green spaces, to explore the built environment influencing factors that can support the diversity of bird species, by surveys in roadside green spaces along the Century Avenue in Pudong New District, Shanghai, and comparing the numbers, density and diversity of bird species between roadside green spaces and the surrounding green spaces. The results show that 1) As small scale green patches, the roadside green spaces can act as shelters and transit stations for birds and other urban wildlife. So in the layout of urban green space system, we should pay attention to the biodiversity supporting services of such “leftover” spaces. 2) Disturbance/interaction edge ratio and setback rate of the first row of trees can have certain influence on the avian diversity of the roadside green spaces, thus minimizing the disturbance of surrounding artificial environment to the wildlife is the main way to enhance the biodiversity of the roadside green spaces. The paper provides a new perspective for the studies of the ecological functions of urban roadside green spaces and the built environment influences on them. The findings can provide scientific basis and methods for the design, construction and management of urban bio-friendly roadside green spaces. They also lay a solid foundation for further exploration of the biological “stepping stone” function mechanism of roadside green spaces in the high density urban ecological green network.