The floristic differences found in the secondary forests of the Yenliao area were sampled by the placement of 35 quadrats of 10 X 10 m over a wide range of habitats. The present study was undertaken to (1) use both clustering and ordinations to elucidate vegetational structure and community relationships; (2) determine the principal factors controlling or closely related with forest composition; (3) evaluate the si;ccessional status of the forests. About 221 species were encountered. Vascular species richness per quadrat averaged 50. The Shannon-Wiener diversity measure of the tree stratum averaged 2.56 (natural Jog) and Simpson's index (complement) averaged 0.92. Dominance is shared by Ardisia sieboldii, Ficus virgata, Cleyera japonica, Ficus fistulosa, Cyclobalanopsis glauca, Schefflera octophylla, Glochidion rubrum, and Persea thunbergii. Three major community types were defined using minimum variance cluster analysis with basal area and species cover data. The results of reciprocal averaging (RA) and principal component analysis (PCA) indicated a strong response in both quadrat and species characteristics to topographical, moisture, and oceanic complex gradients. Analysis of species compositional change across a progression of diameterbased size-strata has been used to reveal the successional relationships which exist between species of tree stratum. It shows a clear trend toward dominance by Bridelia balansae, Persea thunbergii, Ardisia sieboldii and Schefflera octophylla in the near future. Besides, the relative density data for each species' size class were determined, and three population structure patterns were recognized.