The plant community is the product of the interaction between plants and the environment, and the interaction process is associated with changes in community structure and species diversity. Exploring the distribution of forest communities, species diversity patterns, and their relationship with environmental factors is important for protecting forest stability and biodiversity. Quantitative analysis is an important approach in research on community classification and sorting and can profoundly reveal the ecological relationship between plant communities and environmental factors. The study of species diversity patterns can reflect the ecological characteristics of plant communities and their adaptability to environment change. The Korean pine broadleaved forest (KBF) is the local climax vegetation and mainly distributed in northeast China. It has a complex forest structure and rich biodiversity and is very important in maintaining the regional biodiversity. Therefore, it is vital to conduct a case study regarding community classification, ordination, and species diversity patterns in broadleaved Korean pine forests. In recent years, many studies regarding KBF have been conducted from various perspectives, but forest community classification, sorting, and comparison research using quantitative ecology is still lacking. Along a latitudinal gradient, we investigated the forest community structure with 40 plots (20 m×20 m). Then, forest community classification, ordination, and comparison of species diversity were conducted using the methods of MRT (multiple regression tree), CCA (correspondence analysis), and comparison of species diversity indexes. The results showed that the MRT classified the forest communities into four types by relating different aspects of species composition to environmental data:(I) Abies fabri-Pinus koraiensis Association, (Ⅱ) Quercus mongolica-Acer mono-Pinus koraiensis Association, (Ⅲ) Fraxinus mandshurica-Acer tegmentosum-Pinus koraiensis Association, (IV) Carpinus cordata-Betula costata-Pinus koraiensis Association. Species composition and diversity of forest communities differed greatly among the four types. The richness and species diversity index of Carpinus cordata-Betula costata-Pinus koraiensis Association were significantly higher than that of the Abies fabri Craib-Pinus koraiensis Association. The results of CCA were consistent with the forest community classification from MRT. It clearly reflected the distribution range of various community types and the relationships between community distribution and environmental factors. The Abies fabri-Pinus koraiensis Association corresponded to colder habitat, whereas the Carpinus cordata-Betula costata-Pinus koraiensis Association corresponded to warmer and wetter habitat. The Quercus mongolica-Acer mono-Pinus koraiensis Association tended to be in habitats with fertile soil. The distribution of the Fraxinus mandshurica-Acer tegmentosum-Pinus koraiensis Association had no special preference for environmental conditions. Temperature and precipitation were the main environmental factors affecting the distribution pattern of forest communities, whereas soil nutrients had smaller effects. These results help to more thoroughly understand the space distribution pattern and ecological characteristics of the forest community. They also provide the corresponding theoretical basis for the management and protection of broadleaved Korean pine forests in the future.