Government data is the core of national data resources. Building a government big data system and strengthening data aggregation, sharing and utilization are the key to smooth the circulation of data resources, build a high-quality digital government, and promote the modernization of the national governance system and governance capacity. Government data sources are wide and the collection standards are not uniform, which leads to the problems of diversified information sources, large structural differences and difficult alignment. At present, most of the existing researches focus on the application and management of government data, and few studies fully discuss the heterogeneity of government data and the data sharing technology framework based on interoperation. This paper first summarizes the source characteristics and heterogeneity of government data, then analyzes the key technologies of government data sharing based on interoperation, and finally summarizes and looks forward to the government big data system.