With the full-scale breaking out and spreading of U.S. Financial Crisis of 2008，the global financial system has quickly been caught in the worst market crisis since 1929. Such crisis was directly caused by the undue expansion and over-flow of financial derivatives based on the assets securitization and residential mortgage loans securitization in the U.S. real estate market. As far as its legal reasons are concerned，on the one hand，the U.S. financial macro-control policies and financial supervision and regulation systems have some fatal defects in themselves；on the other hand，the financial legal order in the U.S. dollar economy is out of control and supervision. The lessons of U.S financial crisis for China lies in the following five aspects：first，to further strengthen the financial legislation so as to perfect the financial legal system；second，to fully adopt and uphold the sense of financial safety meanwhile to correctly deal with the relationship between the financial safety and financial efficiency；third，to fully implement the moderately loose monetary policy combined with the proactive fiscal policy；fourth，to adopt a rational attitude towards the innovations of financial derivative instrument and strengthen the supervision over and regulation of the financial derivatives；and fifth，to actively promote the reform of RMB exchange rate so as to perfect the managed floating RMB exchange rate system based on market supply and demand.