Abstract: Cyber threats to electric power system have great impact on the national security, public safety and country economy. After years of researches and practices, the United States of America (US) has well formed a multi-party cooperative mechanism for the cybersecurity to safeguard the operation of electric power industry. The cybersecurity framework and strategy for electric power industry in US is presented first. The corresponding duty and its working status of related government agencies and organizations involved in the cybersecurity of the electric power industry is then introduced respectively. The study results and working conclusions of US research institutions and organizations are also briefed. Based on those information, the characteristics of cyber security mechanism in US are studied and analyzed from different points of view including cyber security standard, culture construction, risk management, collaboration and information sharing, and effective response to cyber-attacks. In order to sustain the cybersecurity and evolvement of power information security, not only the standard and specification are required to be continuously improved and actively implemented, but also the culture of security, the risk management, the collaboration and information sharing, the effective response to cyber-attacks are needed to be effectively coordinated and managed.