The niche dynamics during natural restoration process of dominant tree species in montane mixed evergreen and deciduous broadleaved forests at Mulinzi of Southwest Hubei were analyzed by means of Shannow-wiener niche breadth index and Pianka niche overlap index. The results showed that the total breadth of niche of Carpinus fargesii, Cornus kousa var. Chinensis and Cycloblanopsis glauca were higher and theses tree species were found in all five restoration stages. Weigela japonica var. sinica, Carpinus fargesii, Cornus kousa var. Chinensis, Betula luminifera and Ilex wilsonii were the species with the largest niche breadth for the restoration stage of 14, 35, 60, 85 and 110 years respectively. There was a general trend that the niche breadth of dominant deciduous tree species decreased with increasing degree of community restoration, while that of dominant evergreen tree species was on the contrary. When the community restored to its climax stage, the niche of evergreen species in tree layer was close to that of deciduous trees, and that of evergreen species in shrub layer occupied a larger niche; this was a spatial pattern for better sharing of natural resources. With increasing restoration degree of community, the niche overlap between dominant deciduous tree species and other tree species had a trend of fluctuant decrease; while that of dominant evergreen tree species had a trend of fluctuant increase; and the niche overlap among all tree species in communities had a tendency of slightly waved decrease. The results showed that higher niche overlap among the early-succession species with same or similar life form meant a similar or competing requirement on resources. The increase of niche overlap among the late-succession species and other tree species represented a horizontally spatial overlap but vertically spatial differentiation; this is a full use mechanism of different tree species regarding limited resources in their environment.