Abstract: The phylogenetic structure of a community is composed of all genetic relationships between species across the community.Understanding the phylogenetic structure of a community will help reveal the relative importance of habitat filtering,competitive exclusion and the stochastic processes constructing the community.We studied a rare plant community in a 1 hm² permanent plot in Houhe Nature Reserve,Hubei Province.We examined the effects of spatial scales (5 m×5 m,10 m×10 m,20 m×20 m,30 m×30 m,40 m×40 m,and 50 m×50 m) and DBH classes (5 cm≤DBH<10 cm,10 cm≤DBH<15cm,15 cm≤DBH<20 cm,and DBH≥20 cm) at spatial scales (10 m×10 m,20 m×20 m,30 m×30 m,40 m×40 m,and 50 m×50 m) on phylogenetic structure of the community in a subtropical evergreen and deciduous broadleaf mixed forest.The results demonstrated that,with increasing spatial scale,the phylogenetic structure tended to cluster.The degree of phylogenetic clustering decreased with increasing DBH classes.However,the degree of phylogenetic clustering was very high at the scale of DBH≥20 cm.The phylogenetic structures of the communities were random at the scale of 25 m² and clustered at scales of 100 m² and larger,indicating that neutrality may play a leading role at small scales and niche processes may be more important at large scales for community assembly in subtropical evergreen and deciduous broadleaf mixed forest in this case.