Abstract: The species diversity of 18 bush communities of Jiulongshan in Beijing are measured by means of Shannon—Wiener index,And community evenness and ecological dominance of these plant communities are measured also,The Shannon—Wiener species diversity index is around 1.55～3.44,the communities evenness 0.54～0.89,and the ecological dominance 0.12～0.47.The species diversity increases as the habitat condition becomes better,latitude higher,and commtinity structure more complicated.The species diversity has intimate correlation with community structure,which goes up with the ascent of commtinity evenness and goes down when the ecological dominance increases. The restilt of the research will help to raise the level of study on the structure model of natural shrub forest for water and soil conservation.