Abstract: As a national critical infrastructure, the safe and reliable operation of power system is related to power grid security, enterprise security, social security and national security. The United States first raised the cyber security of power critical infrastructure to the national strategic level. At present, a relatively perfect cyber security protection system of power critical infrastructure has been formed. This paper combs the cyber security protection policies and core standards of power critical infrastructure in U.S., deeply analyzes the key objects and methods of cyber security protection of power critical infrastructure in U.S., and gives enlightenment and suggestions, so as to provide a reference for further deepening the security protection of power critical information infrastructure in China.