Nitrogen removal study of municipal wastewater was carried out in A City`s Wastewater Treatment Plant with dual sludge system. The dual sludge system consists of anoxic tank, oxic tank, and clarifier followed by Modified Ludzack-Ettinger(MLE) system. For nitrogen removal, methanol was used as an external carbon source in the anoxic tank. This process showed the effluent quality, achieving 81% of COD_(Cr), removal and 71% of total nitrogen removal. Influent wastewater contained 199∼548㎎/l of COD_(Cr), and 51∼83.8㎎/l of total inorganic nitrogen. The final effluent contained 42∼150㎎/l of COD-Cr and 11.2∼33.5㎎/l of total nitrogen. The specific denitrification rate and C/N ratio in the anoxic tank were 0.1∼0.34 (gNO₃-N/gVSS/d) and 3.06∼4.64 (gCOD consumed/gNO₃-N removed), respectively, at the range of 4∼14℃ of temperature.