Biodiversity in urban areas provides a number of ecosystem functions and services which are critically important for improving urban environmental quality and maintaining urban sustainability.Across the world, urbanization has intensely affected the distributional pattern of biodiversity within and around cities.We surveyed the plant bcommunity of green space in Beijing,including the tree,shrub and herb.the objective of our study is to clear(1) What mainly determine urban plant biodiversity ? land use change? urbanization gradient? (2)How the urbanization select plant? Did it happen in urban, suburb, or even the rural next to urban.Our result showed that although land use change had effects on plant biodiversity, urbanization gradient had greatly changed the distributional pattern of plant biodiversity,not only native species,but also exotic specis.Another, we also found urbanization and land use can’t explain plant community greatly, more complicated fators contributed plant pattern(human, landscape,soil).Finally,Urban plant ecological traits response greatly to urbanization and landuse respectively.In conclution, urbanization have changed plant distribution pattern especially in larger space scale,our result provide important suggestion for urban plant biodiversty protection in the future.