There are more than half of the world's human population living in cities. The vast amount of predicted rapid urbanization in the coming years consuming habitats and reducing the possibilities for wildlife to thrive in cities, and is contributing to the loss of global biodiversity. Among them, birds are the most important part of urban ecosystem and a key target for urban biodiversity protection. Besides, it is also a research hotspot. The last 20 years of urban bird ecology research have experienced exponential growth and now enables literature analyses and reviews. Here, we try to roundup these present findings on urban bird communities research from all over the world, overviewing patterns and variation processes on urban bird community, especially the changes in composition and structure, spatial distribution, living habits and the way of breeding and nesting under this continuous and rapid urbanization. To further assess the importance of and contributions provided by urban green space and vegetation to the urban bird community, exploring its affecting mechanisms that support bird diversity in urban areas, we reviewed the published literature for such studies. The results showed that: 1) Provision of greenery can ameliorate the hostility of the urban environment for wildlife, as well as provide suitable living space and food resources for urban birds. Green spaces provide the most important habitats for urban birds. 2) Not all forms of greening benefit bird communities to the same extent. Compared to those areas that do not pay much attention to native plant protection, areas that retain natural or semi-natural cover and large trees can support richer bird species. 3) Structure and coverage of vegetation have significant impacts on bird communities. The increasing canopy coverage, complex vertical structures and many kinds of plant species can produce various types of plant spaces and heterogenetic habitats. The increased plant spaces and habitats can cause changes in bird community composition, a correspondingly increase in species richness and diversity. In conclusion, maintaining and strengthening the healthy and stable of vegetation communities in cities is an effective strategy to conserve urban biodiversity. Collectively, protecting existing and planting new greenery has great potential to restraint urban biodiversity loss. Based on these, we propose the future research development direction of the relationship between the urban environment and bird communities. Further, the application prospects of this research in bird diversity protection to provide a more resilient, stable, and sustainable urban system are also pointed out.