Understanding the spatial patterns of plant diversity in urban areas is essential for urban planners and managers to effectively manage urban forests. However, thus far, in many cities, plant diversity spatial patterns have been limited at an urban scale by sparse and scattered survey data. This study uses these scattered data in the built–up area of Beijing as a case study to provide a new perspective for exploring the distribution patterns of urban plant diversity. The urban diversity pattern of forest woody plants in this area is mapped via Kriging interpolation in ArcGIS, which allows the estimation of woody plant diversity in areas that have not previously been investigated based on a large amount of field survey data. The results clearly indicate the high– and low–value areas of species diversity within the city, This help in deciding priorities for future protection and management at an urban scale. The geographical detector model is then applied to provide a better understanding of the correlation between urbanization characteristics and woody plant diversity spatial patterns. The results will aid in the development and implementation of suitable policies to change uneven distribution patterns in urban areas. Our applied methodology and results can also be employed to improve basic information on urban woody plant diversity and to offer insights on urban green space planning and management.