Abstract: Mountain Wulian Nature Reserve is located in the southeast coastal region of Shandong Province，to fully understand their community structure and species diversity，the author conducted a field survey，and obtained 11 standard samples，whose total area is 6 600 m2. In samples，the author recorded 141 higher plants，belonging to 52 families.Regional vegetation in this Nature Reserve is evergreen conifer woods-deciduous broadleaverd forest，and deciduous broadleaverd forest，the main forest vegetation is Pinus densiflora-Castanea mollissima community，Quercus acutissima-Pinus densiflora community，P. densiflora-Rhododendron simsii community，Q. acutissima-Rhododendron simsii community.Sample data displays this region xylophyte type is not very rich，but the community structure is complex with obvious environment heterogeneity，indicating tree layer diversity index＜woody layer diversity index＜shrub layer diversity index.The author thinks what affects the diversity of the Wulian core protection areas most is elevation and slope，and the external protection of human interference would seriously affect the vegetation types and species diversity.Overall，the region is in early successional communities，interspecific competition is not sufficient，and the species diversity is low.

Key words: Mountain Wulian, species diversity, community structure, natural secondary mixed forest, field survey