Urban green space provides an important habitat for urban flora and fauna, and is of great significance to the conservation of urban biodiversity. However, the traditional community green space ("traditional green space") mainly focuses on the functions of safety, landscape viewing and recreation, with fewer plant species, and single community structure, which makes it difficult for traditional green space to provide abundant food source and habitat for urban wildlife. Under the policy background of "building green space in the vacated space, where illegal construction was demolished" in Beijing Urban Master Plan (2016-2035), Beijing has built a series of small near-natural community green space ("near-natural green space") in the central city, with different species composition, community structure and management methods from the traditional green space. It is generally believed that biodiversity increases with the increase of green space area in a certain range. For small green space that is highly disturbed by urban surroundings, can the near-natural feature of it significantly improve its biodiversity, including insect and bird diversity? In order to explore the biodiversity characteristics of this kind of green spaces, we investigated the plants, insects and birds in two near-natural community gardens and four traditional community gardens, with sample method and transect method comprehensively, in Xicheng District, Beijing, from August 2020 to March 2021. The biodiversity characteristics between traditional and near-natural green space were analyzed and compared. The results showed that the richness and diversity of shrubs and herbs in the near-natural parks were significantly higher than those in the traditional green spaces, while the evenness of shrubs and herbs in two kinds of green space had no significant difference; the richness and diversity of insects and birds in the near-natural parks were significantly higher than those in the traditional green spaces, while the evenness of birds and insects in two kinds of green space had no significant difference. Compared with traditional green spaces, near-natural green spaces had significantly higher richness of bird-feeding plants and nectariferous plants. In addition, the vertical planting structure was significantly more complex in near-natural green spaces. According to the above results, it is suggested that the area ratio of multi-layered planting should be improved, and the diversity of shrubs and herbs should also be increased in the construction of urban green spaces. The research results not only enrich the biodiversity connotation of small green space, but also provide a theoretical reference for the construction of urban near-natural green space. The research will provide new thoughts for urban park design, reform and management, and guide the sustainable development of green space in metropolis based on biodiversity conservation.