[Purpose/significance] From the perspective of system, this paper investigates the system support of the Privacy Impact Assessment（PIA）in the United States to provide reference for the system formulation of the privacy im? pact assessment in China and provide tools for the government to protect citizens' privacy. [Method/process] Using the research methods of literature research and case analysis, taking the United States as an example, this paper ex? pounds the development process of the privacy impact assessment system in the United States by obtaining first-hand materials through the investigation of literature and website contents, and combs the application of PIA system, PIA au? dit and release process, PIA purpose and significance, and the specific implementation of PIA method. On this basis, it analyzes the interrelationship between the privacy impact assessment system in the United States and the pros and cons. [Result/conclusions] The advantages of the PIA system in the United States lie in the security control of risk analysis, the emphasis on internal government supervision, the focus on the disclosure of PIA, and the emphasis on the update of PIA. The disadvantages lie in the lack of citizen participation and the poor implementation of PIA system. The privacy impact assessment system of the United States has reference significance for the construction and improvement of China's personal information security risk assessment system, especially the construction of privacy risk management system, focusing on external supervision, strengthening the public release of assessment results, and timely updating as? sessment.