Abstract: The mixed broadleaved-korean pine(Pinus koraiensis)forest represents the climax vegetation type of the eastern mountainous area of northeast China. The increasing of the global nitrogen deposition may have affects on every process of carbon cycle. Four levels of N treatments: control(N₀, 0 kg/(hm²·a)), low-N(N₁, 30 kg/(hm²·a)), medium-N(N₂, 60 kg/(hm²·a)), and high-N(N₃, 120 kg/(hm²·a))were set in the present study. We measured soil CO₂ efflux about every half a month during the growing seasons from May 2010 to October 2011 using a Li-6400 portable CO₂ infrared gas analyzer. The results showed that the seasonal variation of soil respiration from all treatment plots was obvious and followed a bimodal curve, absolutely parallel to that of the soil temperature. Soil respiration peaked in June, and presented the lowest values in the early growing season. Soil respiration was exponentially related to the soil temperature at 5 cm depth(R²=0.499-0.692). Soil temperature could explain 49.9% to 69.2% of seasonal variation in respiration. Furthermore, soil temperature and moisture, and incorporating soil moisture into the pure soil respiration-temperature model improved the prediction of soil respiration in N₀ and N₂ treatment plots, and their interactions could explain 52.2% to 73.5% of seasonal variation in soil respiration. The average soil respiration rates in the growing season for N₀, N₁, N₂ and N₃ treatment plots were 3.09, 2.78, 3.06 and 2.90 μmol/(m²·s), respectively, and the corresponding apparent Q₁₀ values were 2.10, 1.93, 1.97 and 2.01. The average soil respiration rate, annual litterfall biomass in nitrogen addition plots were not significantly different compared with those in N₀(P> 0.05).