In 1985, Democratic People`s Republic of Korea(DPRK) concluded a treaty on the border with the Soviet Union and entered into an agreement on the ocean in the following year. This study analyzed the cause, background, contents, and effects of the `The Border Treaty between Democratic People`s Republic of Korea and the Soviet Union` in the 1980s. Through this, this study was to provide a meaningful perspective to understand the situation of Northeast Asia before the collapse of Communist Nations and DPRK`s response. First, under the background of new cold war era in Northeast Asia in the 1980s, the cooperation of DPRK and the Soviet Union was enhanced and the border negotiations were concluded with the proposal of the Soviet Union. Second, the contents of the border treaty were relatively simple and identified the difference in the length of the border between the two countries in the process of conclusion and clarified the setting of the border line and maritime boundary. On the other hand, there was no information on mutual use including military use in the airspace and territorial waters in the Treaty itself. Third, during the period when the border treaty occurred, the activation of the maritime sector, expansion of foreign military relations, and growth of foreign trade were identified in DPRK. These were accomplished based on the favorable atmosphere created by the amicable agreement of `The Border Treaty between Democratic People`s Republic of Korea and the Soviet Union` for DPRK. Since then, DPRK has eased the impact of the collapse of Communist Nations through increased exports of missiles toward Middle East and increased trade with developing countries.