[Purpose/significance] From the perspective of privacy risk assessment and prevention control，this paper investigates the privacy protection practices of government open data in Japan，in order to provide a reference for the development of policy of open data in China. [Method/process] Using the research methods of literature review and case analysis，this paper takes Japan as an example，accesses to the first-handed materials from literature and discusses the experience of government open data privacy risk assessment and prevention in Japan, analyzes and summarizes the legal system of personal privacy protection in Japan, the judgment criteria of personal privacy in government open data, anonymization technology which respond to privacy risk and related posts, institutions that address and relief system which respond to privacy risk, security and control measures and authentication mechanism which respond to privacy risk. [Results/conclusion] This paper put forward to formulate a unified personal information protection law to regulate the scope of personal privacy and safeguard measures. When opening government data, experts familiar with personal privacy protection should be appointed as managers of the implementation of the open data policy so as to have comprehensive consideration on privacy protection at all stages. In addition, before opening data, the identifications of data should be removed and related data should be anonymized to avoid the infringement of personal privacy.