Abstract: The quantitative characteristics of the fallen trees with different decomposition classes in 30 sample plots of four forest types in south Jiangxi Province including the evergreen broadleaved forest, Cunninghamia lanceolata plantation, Phyllostachys edulis plantation and Pinus massoniana forest were studied. The results showed that the biomass and volume of the fallen trees in the four different forest types were individually in the range of 004-146 t/hm2 and 060-2300 m3/hm2. Among the different forest types, both of the biomass and volume of the fallen trees in the evergreen broadleaved forest were the maximum, and there were significant differences in the two indexes between the evergreen broadleaved forest and the other forest types. There was a great difference in the proportion among decomposition classes of the fallen trees, the intermediately decomposed fallen trees accounted for the largest proportion by 607%, while the slightly and heavily decomposed fallen trees took 221% and 172%, respectively. The volume distribution of the fallen trees in south Jiangxi Province was dominated by class Ⅴ diameter trees (middiameter ≥ 20cm), which occupied 364% of the total, followed by class Ⅲ diameter trees (10-15 cm in middiameter), which accounted for 258%, and the class Ⅰ diameter trees (0-5 cm in mid diameter), which accounted for only 03% of the total.