Litter decomposition is a fundamental process to ecosystem functioning being responsible of carbon and nutrient cycling. The decomposition of dead leaves depends on both biotic and abiotic factors. The combination of climate (e.g. mean annual temperature (MAT), mean annual precipitation (MAP), actual evapotranspiration, etc) and litter quality (N content, C/N ratio and lignin content) appeared to be the primary controllers of little decomposition. This is particularly true for temperature, which is inextricably linked to other environment parameters as a mutually confounding factor in terrestrial systems. Global average surface air temperature is predicted to increase 1.1-6.4 ℃ over this century. Climate warming is expected to cause species movements and extinctions, change the composition of communities and alter ecosystem functioning. As decomposition depends strongly on temperature, it is expected to be particularly sensitive to climate warming. However, it is still unclear how climate changes influence little decomposition. As global climate changes, it will become warmer and somewhat drier in forest ecosystems, in northeastern China. Changes in global warming and drying could affect forest distribution. The areas of tropical forests and subfrigid forests might increase and that of temperate forests and boreal coniferous forests might decrease, which might affect little quality by altering the structure and species of the original forest communities. The primary temperate forest in northeastern China is dominated by Korean pine (Pinus koraiensis Sieb.et Zucc.) mixed with deciduous species. Many studies showed that Quercus mongolica will become a main associated tree species in broadleaved Pinus koraiensis forest, because it is more conducive to survival under the environment change in future. Therefore, the process of litter decomposition will be affected by climate warming and composition of little species change. Given that decomposition of dead plant tissues in forest ecosystems regulates the transfer of carbon and nutrients to soil, and represents an important source of CO₂ to the atmosphere. It is necessary to carry out research about litter decomposition of the two species under climate change in future. This study used litter bag methods, the whole process use an alkali absorption in a closed chamber method to measured cumulative CO₂ production. We recognized N concentration and C/N ratio as the litter quality parameters, and calculated decomposition rates as cumulative CO₂ production and initial mass remaining. Microcosm experiments under controlled laboratory conditions have proven useful for investigating the various factors that influence litter decomposition. Thus, this study was carried out through a microcosm experiment, in order to:(i) determine the effect of imitate increase temperature on Pinus koraiensis,Quercus mongolica pure and their mix litter decomposition rate and (ii)the effect of litter with different physicochemical properties on litter decomposition rate at the same temperature level under constant moisture condition, during a time period of 151 days incubation in laboratory. Our results suggest that increased temperature accelerated leaf little decomposition rates within both mixed-species litterbags and single-species litterbags. However, its response may vary depending on the level of increased temperature. When the temperature in closed chamber was at 25 ℃ and 29 ℃, decomposition rates within litterbags decreased in the order of mixed-species > single-Quercus mongolica > single-Pinus koraiensis. When the temperature in closed chamber increased to 31 ℃, decomposition rates was faster within mixed-species litterbags and single-Quercus mongolica litterbags than single-Pinus koraiensis, but the variation between mixed-species litterbags and single-Quercus mongolica litterbags decomposition rates was not statistically significant. This study has great significance on understanding of forest ecosystem carbon and nutrient cycle.