Phylogenetic niche conservatism (PNC) assumes tropical lineages adapt to colder climate and diversify in temperate environment. PNC gains popularity due to its elucidation on latitude and elevational diversity gradient with the availability of comprehensive phylogenetic tree. Here we use angiosperm tree plants collected from 7 mountains on East Asia Islands to test PNC: Lalashan on Taiwan, Miyanoura on Yakushima, Kyushu Mt on Kyushu, Shizuoka and Kurikoma on Honshu, Kariba and Taisetsu on Hokkaido. The standardized effect size of mean pairwise phylogenetic distance (MPD) was used to test PNC with local, island and regional species pools. When considering local mountain species pool, MPD decline with increasing elevation in Lalashan, Yakushima, Shizuoka and Taisetsu which supports PNC, but not Kyushu, Kurikoma and Kariba. This may be due to the specific climate for Kurikoma and Kariba, such as the heavy snow which facilitates plants overwinter. The communities on high elevation of Yakushima, Shizuoka and Taisetsu showed phylogenetic clustered patterns. This could cause by the harsh climates on those mountain tops. The elevational patterns remained the same for all of the mountain but were dominated by random processes when the species pool was expended. Our study showed hierarchical and mountain specific community assembly processes shaped East Asia Island plant biodiversity patterns.