In order to explore the factors influencing the species diversity of plant communities in urban mountain remains, 25 sample mountains were selected based on patch area and kernel density in the urban built-up area of Guiyang, a typical karst mountain city in central Guizhou. On the scale of 20 buffer zones (increments of 100 m, 2000 m in total), four indices of urban matrix, including total impervious surface area, vegetation coverage, fragmentation index and land use, were calculated. The effects of urban matrix characteristics on the species diversity of plant communities in urban mountain remains and their mechanisms were analyzed. The results showed that :(1) The patch area was one of the factors affecting the species diversity of the plant community in the mountain remains. The overall pattern was large for medium > and small BBB>but the effect was low; (2) impervious surface area, vegetation coverage, fragmentation index and land use are the important indicators to explain the impact of urbanization on the species diversity of plant communities in the remaining mountain; (3) of impervious surface area, vegetation coverage, fragmentation index of three indicators of the influence of the remaining mountain plant community species diversity are obvious spatial scale (2000 m), but different area, the density of nuclear remains mountain plant community species diversity of each driver response range and spatial scale effect, no consistent regularity; (4) There is no obvious linear relationship between the formation time of impervious surface of urban matrix and the diversity index of residual mountain. Due to the frequent disturbance of urbanization and multiple human activities, the factors affecting the species diversity of the mountain plant communities in the karst mountain cities are very complex and diverse. The species composition and diversity characteristics of the plant communities are the result of the comprehensive action of multiple factors and multi-scales.