A long-term tracking experiment on coarse woody debris (CWD) decomposition of 11 temperate tree species was established in northeastern China in 2004. The objectives of this study were to (1) compare differences and changes in structural components of the CWD and CO₂ flux released from CWD decomposition (R_CWD) during the initial three years; and (2) examine relationships between the structural compositions and R_CWD during this period. The experimental design was completely randomized blocking design with 11 species × 6 blocks × 4 sites. The tree species investigated included softwood species (Betula platyphylla, Populus davidiana, and Tilia amurensis), hardwood species (Juglans mandshurica, Phellodendron amurense, Quercus mongolica, Acer mono, Fraxinus mandshurica, and Ulmus japonica) and coniferous species (Pinus koraiensis, Larix gmelinii). The four sites were a dry oak forest, a wet hardwood forest, a medium moist pine plantation, and an open field. The R_CWD was measured with an infrared gas exchange analyzer (LI-6400 IRGA) from May to October in 2005 and 2008. Three 5 cm thick dics of CWD samples for each tree species were randomly sampled in October 2005, and six samples in October 2008 at each site for determining lignin concentration (L_c,%), lignin density (L_d, g/cm³), holocellulose concentration (H_c,%), and holocellulose density (H_d, g/cm³). The results indicated that the L_c and H_c differed significantly among the species (P<0.001), with the softwood tree species being the least L_c. The ratio of lignin to nitrogen concentration (L_c/N) ranked as: coniferous species > hardwood tree species > softwood tree species. The L_c during the initial three years of decomposition increased for all species except for T. amerensis and U. japonica, but the changes were insignificant (P> 0.05). The H_d and L_d decreased to some degrees (P<0.05), with the minimum loss in the coniferous species and the maximum loss in the softwood species. The L_c/N increased during the decomposition for all species. The normalized R_CWD to 15 ℃ of the CWD temperature (R₁₅) differed significantly among the tree species. The R₁₅ for the broad-leaved species was higher than that for the coniferous species. The temperature coefficient of R_CWD (Q₁₀) showed a similar trend among the tree species as the R₁₅, fluctuating between 2.41 (coniferous species) and 2.71 (broad-leaved species). After the three years decomposition, the R₁₅ decreased for all species except for the L. gmelinii, A. mono, and F. mandshurica. Overall, the R₁₅ of the softwood species decreased by 32.0%, and that of coniferous species increased by 23.1%. Additionally, the Q₁₀ increased for the coniferous species, and remained relatively stable for the broad-leaved species. The R₁₅ was positively correlated with the H_c,but negatively correlated with the L_c and L_c/N. The changing rates of R₁₅ during the initial three years were positively correlated with those of H_c, suggesting the major contribution of structural compositions to the changes of R_CWD.