Abstract: The rare and endangered Acer pentaphyllum trees were only distributed in the arid valley area of the upper and middle reaches of the Yalong river, and now they were found in Yajiang, Jiulong, Kangding and Muli counties of Sichuan province. In this paper, investigation and analysis were made of the species diversity and niche characteristics of Acer pentaphyllum community in each distribution location. The results showed that (1) because the Acer pentaphyllum community was located in the Yalong river arid valley area, the species diversity of community was not high. (2) The niche breadth of the population of Acer pentaphyllum was large, but the niche overlap with other species was not high, indicating that it was a specialization of the arid valley region. (3) The niche overlap among other species in the community was generally high, showing that other invasive species were disorderly, the level of niche differentiation was low, and the competition among species was fierce. It could be seen that the cause for the danger of Acer pentaphyllum was not from the direct competition of other species, but more probably due to the unique biological characteristics of its niche specialization.