Abstract: Taking four typical forest communities（spruce, fir, red pine forest, birch forest, poplar forest, and Mongolian oak forest） within the protected area as research objects, this study explored the species composition, community structure, and species diversity of forest communities in the Taipinggou National Nature Reserve in Heilongjiang Province through field investigation and redundancy analysis methods. The research results indicated that there were a total of 164 plant species belonging to 62 families and 124 genera in the four community types. The species richness of the tree layer and shrub layer of the four community types was lower than that of the herb layer. The species richness index of the spruce, fir, and red pine forest was shown as herb layer（3.06）, tree layer（2.89）, and shrub layer（1.64） from large to small. The species richness index of the birch forest showed from large to small in the herb layer（3.22）, shrub layer（1.02）, and tree layer（0.33）. The species richness index of poplar forest showed from large to small in the herb layer（5.09）, tree layer（1.29）, and shrub layer（0.89）. The species richness index of Mongolian oak forest showed from large to small in the herb layer（4.74）, shrub layer（0.88）, and tree layer（0.59）. Outside the herb layer, the species diversity indices of the spruce, fir, and red pine communities were Menhinick richness index（R）, Pielou evenness index（E）, Shannon-Wiener diversity index（H′）, and Simpson diversity index（H）, which were higher than the other three communities. The values of the four indices for the tree and shrub layers were 2.89, 0.90, 2.21, 0.90, and 1.64, 0.94, 1.67, and 0.83, respectively. The community characteristics were quantified from multiple indicators such as slope, altitude, tree height, canopy density, shrub height, and herb height. From this, it can be seen that the vertical structure stratification of the four forest communities in the protected area was obvious, among which the dominant species in the tree layer were obvious, and the importance value of the dominant species was much greater than that of other accompanying species. The species importance values in the shrub layer and herb layer were relatively scattered. The total richness of the spruce, fir, and red pine communities was mainly influenced by the combined effects of the tree and herb layers, while the total richness of the other three communities was mainly influenced by the richness of the herb layer. Sorting analysis showed that slope, tree height, and canopy density were significant factors that cause diversity changes. Through the above research, we aim to provide scientific basis for the conservation of biodiversity in this protected area.