Exploring the differences and coupling relationships of species diversity and stand characteristics could provide data with which to improve biodiversity and ecological services of natural forests. In this study, three typical communities of larch forest, shaw (mixed forest with various tree species), and birch-larch forest were selected at Huzhong in the Daxinganling mountains for measuring stand characteristics (height, diameter at breast height[DBH], crown width, coverage, and others), richness index, diversity indexes, and evenness indexes of the arbor layer, shrub layer, and herb layer. Canonical correspondence analysis (CCA) was used to uncover their differing associations among forest types, together with a multiple analysis of variance to detect the inter-forest differences. The results showed that (1) the height and clear tree bole height of the arbor layer differed with shaw > larch forest > birch-larch forest (P < 0.05); DBH of the larch forest was 6% and 11% higher than that in the birch-larch forest and the shaw, respectively. There were no significant differences in the shrub layer in the parameters of height, canopy coverage, ground diameter, crown width, as well as in the herb layer for species abundance, herb coverage, and herb height. (2) The maximum species richness, Shannon-Wiener index, and Simpson index of the arbor layer, shrub layer, and herb layer all occurred in the shaw relative to the larch forest and the birch-larch forest. Moreover, the herb layer showed the same pattern as in the arbor layer, i.e., shaw > birch-larch forest > larch forest; however, the shrub layer exhibited a different order, with shaw > larch forest > birch-larch forest. The species evenness of the arbor layer in the birch-larch forest and shaw were approximately three times that of the larch forest; however, there was no significant difference in the shrub layer and the herb layer (P > 0.05). (3) CCA showed that the correspondence associations between community characteristics and species diversity differed among the three forest types. In general, for all three forests the characteristics of the shrub (ground diameter and crown width) and herb layer (coverage, abundance, and height) had a substantial influence on plant species diversity. Plant diversity was significantly affected by tree DBH in the birch-larch forest and the shaw; however, it was highly significantly affected by tree height in the larch forest. With the increase of shrub coverage and herb height, herb diversity decreased; whereas decreasing herb diversity usually corresponded with increasing diversity of the arbor and shrub layer in the shaw. In the larch forest, herb height increase, together with decreases in abundance and coverage usually corresponded with a decrease in herb diversity, and increases in arbor and shrub diversity. An increase in shrub diversity was usually accompanied by a decrease in arbor and herb diversity, but corresponded with increases in tree DBH, herb abundance, and coverage, and decreases in shrub crown width in the shaw; however, it was accompanied by decreases in shrub crown width, as well as herb abundance and coverage in the birch-larch forest. Our findings highlighted that community characteristics were closely coupled with species diversity, and the above-mentioned decoupling results will favor diversity conservation through maintaining good forest structure in the Daxinganling Mountain Region, Northeast China.