After the Second World War, great and profound changes have taken place in the international situation. First of all, with the increasing trend of world economic globalization, new changes have taken place in the relations between imperialist countries, that is, from pre-war military struggle to all-round competition, coordination and cooperation. So that the capitalist world presents a fairly stable state. Although the law of unbalanced development of imperialist economy and politics still exists, the contradictions and struggles caused by this unbalanced development are no longer manifested in the military field, but concentrated in the economic field. Therefore, war can be avoided. Secondly, class contradictions in capitalist countries have been relatively eased. After World War II, the great inventions and discoveries of new technologies promoted the rapid development of social productive forces and the continuous improvement of people's living standards. In addition, in order to enhance the social and economic functions of capitalist countries, the bourgeoisie has implemented some improvement measures, which have eased the basic contradiction of capitalist countries-the contradiction between the bourgeoisie and the proletariat, and the proletarian revolution will be difficult to achieve for a period of time. Third, with the independence and liberation of the former, the contradiction between colonial and semi-colonial countries and imperialist countries has undergone new changes, and the contradiction between them has been transformed into an unequal political and economic contradiction between developing countries and developed countries. The basic contradictions in the world and the major and profound changes in the international situation have quietly changed the theme of the times. The development and change of world contradictions after the war. After World War II, great changes have taken place in the balance of international political power, and two systems and three types of countries have emerged, such as developed capitalist countries, socialist countries and developing countries. The relationship between them constitutes a global strategic issue in today's world. The relationship between these three different member States can be summarized as "East-West, North-South", and the basic contradictions in the national society are mainly "East-West contradiction" and "North-South contradiction". Second, the strategic balance and global strategic deployment of the two superpowers, the United States and the Soviet Union, were not completed, which restricted the outbreak of the world war. After World War II, the United States and the Soviet Union competed to develop nuclear weapons and conventional weapons for world hegemony. On the whole, the two sides are evenly matched, both big enough to destroy each other many times, thus forming a state of "nuclear terror balance." If the United States and the Soviet Union can't fight, there will be no world war. Third, the growth of world peace forces exceeds the growth of war forces. In the 20th century, mankind experienced two world wars and paid a great price. People all over the world no longer want to see war anywhere in the world, but long for permanent peace in the world. Therefore, opposing war and safeguarding world peace have become the common pursuit and strong desire of people of all countries. After World War II, a large number of newly emerging national independent countries and socialist countries created extremely favorable conditions for world peace and development. Fourth, science and technology have replaced war as the main means to obtain economic benefits. After World War II, the third scientific and technological revolution marked by atomic energy, computer and space technology rose in developed capitalist countries. In addition, the scientific and technological revolution has greatly promoted the change and adjustment of the economic structure and created a large number of new industries. The national reality after World War II shows that the economic benefits obtained by improving the level of science and technology far exceed those obtained through war. Fifth, economic globalization has made development a global issue. On the one hand, the globalization of the world economy and the development of regional economic collectivization have deepened the degree of mutual penetration, mutual restriction and interdependence among countries, and the existence of common interests has promoted the continuous development of international coordination and cooperation mechanisms. On the other hand, economic globalization also makes development a global issue. Economic globalization has further deepened world economic ties, and the economic difficulties faced by developing countries are not only their own problems, but also greatly affect the further economic development of developed countries.