Abstract: Information security clearance has become a significant process to safeguard classified national security information and/or occupy a national security sensitive position. The United States Federal Government has a excellent security system with historical experience and prominent characteristics in both procedure and system, such as strict clearance procedure and an integration of rights and responsibilities. This article makes an in-depth introduction of the security clearance of the public sector in America and compares it with which in the private sector and with Chinese political censor, revealing some obvious deficiencies of the censor in target definition, procedure effectiveness, content comprehensiveness, manner diversity and system continuity. With the useful experience of the United States in the field of information security clearance, we need to reform our political censor system and explore a security clearance system with Chinese characteristics.