This articles aims to examinethe processes of reorganizing the defense system in Hamheung, Macheonryeong(磨天嶺), and Cheolryeong(鐵嶺) which were the main defensive areas in the southern part of Hamgyeong Province during the late Joseon Dynasty. After the ascent of the Qing Dynasty in Manchuria at the beginning of the seventeenth century the priority in the defense of Hameyeong Province was given to the inland Hamheung area amongst the existing Six Frontier Positions(六鎭). Accordingly the attempts were made to reorganize the defensive installations and to expand the defensive strength in Hamheung area and its neighboring passes. At the same time the progress was made for the reorganization of the defense system in the whole area of Macheonryeong pass, an approach linking the northern part of Hamgyeong Province to the inland areas. In the mideighteenth century the defense system was completed in the whole areas of the Sambang(三防) and the Cheolryeong pass, an approach linking Hamgyeong Province to Gangwon Province. However, the development of the areas bordering with Qing China in the second part of the eighteenth century reduced the significance of the defense system in the southern part of Hamgyeong Province.