Based on the community survey in 48 sampling areas, we use the samples to signify the comprehensive state, and the species importance values as the state index of niche instrumentation. We employ Levins and Schoener indices to study niche breadth and niche overlaps of three layers of arbor, shrub and herb in paleo-periglacial areas of Mt. Laotudingzi, eastern Liaoning mountainous region. The results show: (1) In the arbor layer, the niche breadth of Abies nephrolepis, Tilia amurensis, Acer barbinerve, Betula ermanii and Picea jezoensis var. komarovii are much larger than that of others, among them, the Abies nephrolepis is the generalized arbor seed, and Tilia amurensis is the constructive species of forest community below 800 m, while the Acer barbinerve, Betula ermanii and Picea jezoensis var. komarovii are the constructive species of forest community above 800 m. The value of niche overlap between Abies nephrolepis and Picea jezoensis var. komarovii is as high as 0.616, showing that these species had similar biological characteristics, and adapted to each other in the long-term process of communities succession, which formed an optimal survival state in the dark coniferous forest. (2) In the shrub layer, the niche breadth of Actinidia kolomikta, Lonicera subhispida, Euonymus macropterus and Syringa velutina are larger than that of others, which has already evolved into the generalization plants of the deciduous broad-leaved forest and mixed needle- and broad-leaved deciduous forest. The values of niche overlaps between Actinidia kolomikta and Lonicera subhispida, Syringa velutina, Euonymus macropterus, Euonymus pauciflorus range from 0.515 to 0.610, which have high similarity of demand for environmental resources between all these species. (3) In the herb layer, the niche breadth of Aegopodium alpestre, Meehania urticifolia, Oxalis corniculata, Circaea alpine are larger than that of others, which has already evolved into the generalization plants. The value of niche overlaps between Aegopodium alpestre and Meehania urticifolia is as high as 0.702, and the values between Oxalis corniculata and Circaea alpine, Spuriopimpinella brachycarpa and Aegopodium alpestre, Spuriopimpinella brachycarpa and Phlomis maximowiczii are from 0.556 to 0.580. (4) The niche overlaps between major populations were quite common, but the overlap degree of species was relatively less, part of the species niche even separated completely, which shows that it is not so fierce for the major plant populations to compete for the same environmental resources.