Abstract Economic sanctions have attracted a great deal of attention in recent years because of their increased use and the substantial economic and social costs they impose on targeted countries, businesses and individuals. They also create considerable opportunity costs for firms and investors in the countries of the sanctioning states and major implementation challenges for both developed and developing states. United States, as the most powerful state in the world, always puts great emphasis on the use of economic sanction. After the Second World War, in order to build and maintain world hegemony, the United States frequently applies economic sanctions against other countries. This not only brings disaster to the target country and people, but also makes itself suffer huge economic losses. Regarding economic sanctions, many scholars have focused on the research on the effectiveness of economic sanction, but few have researched on the incentives leading to their employment. In this essay, we not only focused on the effectiveness of economic sanction but also analyzed the conditions that led to its use. The case study method is adopted to analyze the questions. The thesis contains two important case studies as follows: the United States economic sanctions against China on human rights and proliferation issues and the U.S economic sanction against Iraq. Key Words: Economic Sanctions; Foreign policy; Unites States sanctions against China; China; U.S sanctions against Iraq; human rights;