Using Levins and Shannon-Wiener niche breadth index, the niche of Betula luminifera population and its main associated tree species in Fuyuan County, Yunnan was studied. The results showed that B. luminifera had the biggest niche breadth. The niche breadth of Cunninghamia lanceolata, Pinus armandi ranks second. The niche breadth of other associated tree species was smallest. It indicates that B. luminifera has extensive adaptation to environment and it is the dominant species in the community. The niche proportional similarity between B. lumini f era and C. lanceolata, P. armandi was larger, showing that B. lumini f-era and C. lanceolata, P. armandi had greater resource-sharing degree. But the niche proportional similarity between B. lurninifera and most of other associated tree species were small. The niche overlap between most of tree species in B. lurninifera community were smaller, which indicated a higher niche polarization of main tree species and a weaker competition in B. lumini fera community.