Abstract: In the early period after World War Ⅱ, the Korean election under the UN inspection had to be held only in southern Korea due to the confrontation of the Soviet-American relations, which caused the separation of Korea into two parts. After the outbreak of the Korean War, the U.S. promptly intervened in the war in the name of the UN under the condition that the Soviet Union hadn’t returned to the Security Council in time. With the early military success of Chinese Peoples’ Voluntary Army, the Soviet Union rejected to accept the UN ceasefire suggestion, which led to the missing of a chance to end the War as early as possible. When the War came into a deadlock, the communication between the Soviet Union and the US through the UN channel promoted to open the door of the armistice negotiations. After the issue of prisoners of war (POW) was submitted into the UN, the Soviet’s adherence to the principle that all POWs should be repatriated unconditionally made the UN reach no conclusion. In short, the Soviet-American game on the Korean issue in the UN framework often results in a zero-sum rather than a win-win situation, which has had an important impact on the intensification of the Korean War and the delay of the armistice negotiations.