Abstract: Forest soils contain about 45% carbon (C) of the terrestrial soils, and thereby minor changes of C in forest soils can significantly alter the content of atmosphere carbon dioxide (CO2). Forest litters are the principal source of C pool in forest soils, which can change C and nitrogen (N) transformations by altering the soil moisture, temperature, pH, and nitrogen and N sources into soil during the process of decomposition. However, the effects of forest litters, especially litter mixtures on soil C, including total organic cC (TOC), dissolved organic C (DOC), microbial biomass C (MBC) are not well understood in the southwest China. Mixed leaf litters from dominated trees of Castanopsis platyacantha – Schima sinensis forest in Mt. Wawu National Forest Park, i.e. Machilus pingii (MP), Castanopsis platyacantha (CP), Schima sinensis (SS), MP CP (MPCP), MP SS (MPSS), CP SS (CPSS), and MP CP SS (MCS), were incubated at 20 oC using the litter bag method in the laboratory. Mass remaining of leaf litters, and TOC, DOC and MBC in the soils were studied at 14, 42 and 84 days of incubation, and correlations of TOC, DOC and MBC were also determined. The results showed that the litters decomposed quickly with an incubation of 0-14 days, and slowly with an incubation of 14-42 days during the period of 84-day incubation. The rates of mass remaining of MP litters were the highest among all litter treatments, being 97.3%, 96.3% and 93.4% and those of CP SS litters the lowest, being 91.1%、88.6% and 85.3% at 14, 42 and 84 days of incubation. All litters increased the decomposition rates during the 84 days of incubation, except for MPSS at 14, 42 and 84 days of incubation and MCS at 42 days of incubation. The decomposition rates of leaf litters followed the order by CPSS > SS > MCS > MPCP > CP > MPSS > MP at the end of incubation. Litter decomposition rates were related to litter physical properties such as hardness and permeability. Compared with the treatment without the litters, TOC was significantly stimulated by the decomposing litters of MPCP, CPSS and MCS, but DOC was significantly inhibited by these litters after 14-day incubation. MBC was significantly increased by the decomposing litters of MCS, and sharply decreased by the MPCP and MPS litters in the first 14-day of incubation. An increase of TOC and DOC was only found in the soils with the decomposing litters of MPSS and CPSS after 42-day incubation. However, only the litters of MPCP, MPSS and MP significantly reduced soil MBC. There were no significant impacts of all the leaf litters on soil TOC and DOC, although the litters of CPSS, MCS, SS and MPCP significantly promoted MBC, and those of CP significantly depressed MBC after the 84-day incubation. Organic C in the soils with the litter mixture was higher than that with the addition of litters of individual tree species. TOC was significantly stimulated by all of the mixed litters while DOC was significantly promoted by CPSS after the 14-day incubation. TOC increased in the soils with CPSS, and DOC was enhanced by the MPCP, MPSS and CPSS after the 42-day incubation. MPSS sharply promoted soil TOC and DOC, and MPCP, CPSS and MCS significantly stimulated MBC at the end of incubation. The relationships among the leaf litter decomposition rates, TOC, DOC and MBC differed at different stages during the process of decomposition. The results suggested that the effects of litter types and mixtures on the litter decomposition rates, and soil TOC, DOC and MBC could be positive, negative and insignificant, which were dependent on the litter quality and nutrients released from the litters during the decomposition. Key words: litter quality; decomposition rate; total organic carbon, dissolved organic carbon, microbial biomass carbon