Abstract: From November 2012 to May 2013, one 1-hm2 permanent monitoring forest plot was established at a Schima superba and Pinus massoniana forest in Zhuji Dongbaishan Provincial Nature Reserve, Zhejiang province for long-term investigation on species diversity. Analysis was made on niche breadth and overlap of the top 15 dominant species in the plot by using Levins niche breadth as well as Levins niche overlap formula. The results showed that the important value of S. superba and P. massoniana showed dominant position in the community, indicating that they were the constructive species in the community. The niche breadth of S. superba was significantly larger than that of the others, resulting that S. superba played decisive roles in maintaining the community structure and function as well as creating microenvironment within the community, and it occupied the main ecological position on the resource axis. The niche breadth of P. massoniana, Lithocarpus glaber and Castanopsis sclerophylla was relative larger, while that of Loropetalum chinense and Albizia kalkora was relatively smaller. This indicated that these species had narrow ecological adaptability in resource, and their ability to use environmental resources were relative weak. There were 5 pairs of tree species (4.76%) with niche similarity ratio above 0.6, 12 pairs of tree species (11.47%) with niche similarity ratio above 0.5, and 56 pairs of tree species (53.33%) with niche similarity ratio above 0.2. There were different degrees of niche overlap among different dominant species, and the niche overlap among the main dominant species was significantly higher than that of other species. This study will give ecologist new insights into further understanding the actuality of Dongbaishan forest, and provide reference for restoration, reconstruction, conservation as well as management of zonal vegetation in this area.