Resources position by different habitat gradient populations were taken according to the investigation data of major forest group and plant multiplicity in Nan'ao Island.Total eight resource positions were selected to explore the niche breadth,overlap and proportional similarity of major population of Acacia confusa forest.The results showed that the difference of niche breadth among populations was significant.The larger the populations,the more important the niche breadth they have,while the similarity degree of using resources was generally small.The niche proportional similarity among Acacia confusa and the species with broad niche breadth was much greater,such as Pinus massoniana,Schefflera octophylla,Phoebe bournei and Litsea glutinosa.They held the same similar requirements to the habitat and formed the mixed forest easily because of high niche overlap.The results had instructive importance to ecological research and productive practice of Acacia confusa forest as well as water conservation forest in Nan'ao.