Abstract: The exposure of PRISM scandal has been stimulating global discussions on both national security and privacy protection. Surveying on foreign intelligence surveillance programs of National Security Agency, under the legal framework of cyber surveillance in the U.S., it reveals that these surveillance programs enjoy so clear and precise applying scope, strict examination and supervision system and rigid procedure regulations that the U.S. government can maintain national security interests, as well as do utmost to protect public privacy with legal supports. Both building a two-win relationship between governments and Internet companies and improving legal system and legal procedure are meaningful steps to China.

Key words: cyber surveillance system of the United States, legal protection, PRISM scandal, cyber security