Abstract：The World War II ended with the victory of the allied countries and the world people. While, shortly after the war, the cold war broke out between two most important anti fascist allied countries: the USSR and the U.S.A.. Of course all these did not happened in one night. There was a relatively long period: The early period of the postwar (1945-1949) was the transitional phase. This article argues about the diplomacy of the Soviet Union in this time, which took the realistic progressive defensive foreign policy. For carrying out this policy, its revolutionary characteristic gradually faded but the conservative nature reinforced, so the conflict between the two countries changed from that of the ideology into the hegemony.
