<p>Mixed deciduous-evergreen needleleaf forests (MNs) are widely distributed in the northern hemisphere. However, the issue whether MNs are climax forests or transitional ones is remaining uncertain. Based on 1318 plots surveyed across China, we aim to clarify this issue by comparing the differences in species composition and environmental characteristics between MNs and other two similar coniferous forest types, i.e., evergreen needleleaf forests and deciduous needleleaf forests at both the national and regional scales. The results indicate that MNs have distinct floristic composition and diagnostic species in most cases. Specifically, species richness and the importance value of rhizomatous herbs in MNs are significantly higher than in evergreen needleleaf forests observed at the national scale and in some cases at the regional scales. In addition, the importance value of tussock herbs in MNs tends to be lower than in deciduous needleleaf forests, but woody species abundance in MNs is significantly higher than in deciduous needleleaf forests observed at the national scale and in some cases at the regional scales. With respect to environmental characteristics, MNs tend to preferentially grow in the habitats with lower precipitation, moderate temperature, semi-shady or semi-sunny, and lower to mid-slopes in nature compared to other two similar coniferous forest types. Our findings thus indicated that MNs represent a climax forest type rather than a transition between two vegetation types only.</p>