Long-term plots are important platforms for research on forest ecosystem characteristics, processes, and functioning such as species spatial distribution, community dynamics, and mechanisms for the maintenance of biodiversity. Many long-term forest plots have been established in subtropical China, but most of them are broadleaf forests. Plots that focus on coniferous (and broadleaf mixed) forests in that region are still scarce. Following the field protocol of the large long-term plot on Barro Colorado Island in Panama, a 6.4 hm² mid-subtropical coniferous and broadleaf mixed forest long-term plot was established in the natural distribution area of Tsuga chinensis var. tchekiangensis (Pinaceae) at an elevation of around 1800 m in Jiangxi Wuyishan National Nature Reserve in 2014. The first inventory of woody plants with diameter at breast height (DBH) ≥ 1 cm in the plot showed that (1) there were a total of 89 woody species belonging to 53 genera of 29 families; these values were significantly lower than the averages of subtropical broadleaf forest (SBF) plots, but significantly higher than those of temperate coniferous (and broadleaf mixed) forest (TCF) plots in China. (2) Tropical areal types were the major floral components at the family level, whereas temperate areal types were the major floral components at the genus level. (3) The density of independent individuals was 2252/hm², which was similar to the average of TCF plots, but significantly lower than that of SBF plots. (4) The basal area at breast height of the plot was 37.89 m²/hm², which was similar to the average of SBF plots, but significantly lower than that of TCF plots. (5) Canopy layering was evident and dominant species were distinct in the community. The sum of the abundance of the four most-abundant species was as high as 55% of the total abundance; however, the sum of abundance of the 40 least-abundant species was only 1% of the total. (6) The DBH distribution of the community appeared as a reversed ‘J’ shape. The number of small-size (DBH ≤ 10 cm) individuals was around 76.9% of the total abundance, whereas the number of large-size (DBH > 30 cm) individuals was only 5.3% of the total. (7) For the major species, DBH distribution shapes appeared as various types, such as a skewed distribution and ‘L’ shape, but spatially they all showed aggregated distribution patterns within the plot. (8) Though T. chinensis var. tchekiangensis was the most dominant species at the current successional stage, its recruitment rate was low. These findings demonstrate important values of this long-term plot for the monitoring of forest biodiversity and conservation of T. chinensis var. tchekiangensis in China.