A 0.96 hm² plot was established in a subtropical evergreen broad-leaved forest in the Chishui Alsophila National Nature Reserve, Guizhou province. The 2299 individual trees were stem-mapped and classified into three height classes:lower, intermediate, and upper height class. Diameter at breast height (DBH) and crown width (CW) were recorded as additional measures of individual growth and performance. In this study, the spatial distribution patterns, spatial associations, and competition among different tree height classes were analyzed PCF (Pair-correlation functions) Analysis based on individual distances. MCF (Marked correlation functions) based on individual DBH and CW were used to detect spatial patterns and within and between different size classes. We found that:(1) The upper tree species showed random distributions at almost all scales. The middle and lower tree species clustered on the small scales of 0-6 m, which showed positive associations with each other within a 1 m scale. (2) No intra-class competition of individual trees within the upper height class was detected, nor was there a significant association with other classes. (3) Intra-and interclass competition in the lower and intermediate height classes had some negative influence on the growth and spatial distribution of individuals. This suggested that individuals among different height classes were at different succession stages in the subtropical evergreen broad-leaved forest in Chishui. Intra-and interspecies competition had the least influence on the upper height classes, but significantly influenced the intermediate and lower size classes, resulting in an aggregated distribution of lower and intermediate height individuals at small scales. This study helps explain competition strategies and coexistence between different height classes. Additionally, it verified the high sensitivity of the marked correlation function analysis in the competition detection of a plant community.