The level of urban biodiversity is an important indicator reflecting the level of harmonious coexistence between human and nature, and is of great significance for promoting sustainable urban development. The expansion of cities and their infrastructures has changed the original ecosystem, hydrological condition and surface structure of the land. The accelerating urbanization process has caused serious impacts on biodiversity, and urban biodiversity conservation has become an important and urgent task in urban ecological construction nowadays. Unlike traditional biodiversity research, urban biodiversity conservation is based on the premise of biodiversity conservation, and seeks to use biodiversity scientifically to bring wider economic and social benefits to cities. The current urban biodiversity research results are abundant and multifaceted, but still face key problems such as lack of systematic and holistic evaluation framework and transboundary and multi-scale management. Therefore, this paper reviews the research on urban biodiversity at home and abroad, summarizes the current criteria and methods of urban biodiversity evaluation, and introduces the urban biodiversity enhancement from the perspectives of international cooperation, national policies, urban planning, special conservation, and nature-based solutions from the main challenges of urban biodiversity conservation. The article discusses the pathways of urban biodiversity enhancement from the perspectives of international cooperation, national policies, urban planning, special conservation and nature-based solutions. Finally, the article discusses the concerns and future research directions of urban biodiversity, and proposes policy recommendations for urban biodiversity conservation to provide reference for the preparation of biodiversity conservation plans and urban biodiversity conservation work in different regions, with the aim of promoting urban biodiversity conservation and the harmonious development of human and nature.