As a special kind of participant in financial markets, SIFI has negative externalities which could lead to the moral hazards in the financial markets, harm the fair competition orders and expose taxpayers to loss. Under the traditional supervision principle of the "Too Big to Fail",this kind of negative exerternalities arising from SIFI could not be adequately addressed. Consequently, the new financial regulatory reform Act in U.S.strengthens the supervision of the SIFI, constructs the comprehensive resolution regimes of SIFI and terminates the application of the "Too Big to Fail". It is the balance that U.S. government pursues the security of the financial system and defends the social public interests. Drawing on the changing ideas and relevant arrangements of U.S., China should focus on four key areas during the construction of the legal regulation system of SIFI:the establishment of SIFI supervisor; the assessment standards of SIFI; the risks aversion and crisis resolution of SIFI.Only by this way, can we rectify the misunderstanding of the "Too Big to Fail"and realize the double-win aim that can ensure the stability of financial markets and protect the public interests.