Abstract: 【Objective】 To study the short-term decomposition laws of coarse woody debris（CWD） in subtropical low mountain and hilly secondary broad-leaved forests under different decomposition levels,it can provide a deep understanding of the CWD decomposition mechanism and carbon in the subtropical forest ecosystem under the background of global change.【Method】 The secondary broad-leaved forest in the Maoershan National Forest Park,Taining,Fujian Province,was chosen as the research site. The coarse woody debris were classified into five decomposition levels,and the decomposition rate and nutrient content of CWD with different decomposition levels under the forest were measured.【Result】 The mass residue rate after one year of CWD decomposition is sorted by size:Ⅴ（69. 10%）＞Ⅳ（58. 30%）＞ Ⅱ（56. 68%）＞Ⅰ（45. 22%）＞Ⅲ（31. 06%）. The decomposition rate of CWD follows the single-factor exponential model,and the order of the k values is as follows:Ⅲ（1. 215）＞ Ⅰ（0. 871）＞ Ⅱ （0. 592）＞ Ⅳ （0. 489）＞Ⅴ （0. 348）.The decomposition rate of decomposition level Ⅲ is significantly higher than other classes（P＜0. 05）,and the time required to decompose 95% of CWD for the five decomposition classes is Ⅴ （8. 609 a）＞ Ⅳ（6. 127a）＞Ⅱ（5. 061 a）＞Ⅰ （3. 440 a）＞Ⅲ（2. 466 a）. During the one-year decomposition process,the TC and Mg content of CWD gradually decreased,and the TN,TP,and TK content first decreased and then increased,the Ca content first increased and then decreased;after one year of decomposition,the TC residual rate of the 5 decomposition classes of CWD was all around 50%,and the Mg residual rate of classes Ⅰ,Ⅱ,and Ⅲ was 30%. TC and Mg were all net released. TP of classes Ⅰ and Ⅲ are shown as net release,and TN,TP,TK and Ca of class Ⅴ are all shown as net accumulation.【Conclusion】 Although there is a net release of elements,the release rate of TC and other key elements is slow,so coarse woody debris in secondary broad-leaved forest is an important C pool and a long-term source of elements in the forest.