Since July，2007，the “Subprime Mortgage” bubble of American real estate began to burst，and then led to the whole crisis of financial system in 2008，which triggered the largest financial crisis since 1929. As this crisis is caused by the collapse in “Subprime Mortgage” market of American real estate market，it is also named “Subprime Crisis”. The U.S.“Subprime Crisis” spread to the world through a variety of securities，so any financial fluctuations in the U.S.produced butterfly effect in the world. The euro zone plunged into severe economic depression.