Based on the current establishment of China’s social credit system，the transformation of government functions，the reform of the market supervision and social governance，the article expounds the basic issues in the study of public credit theory. This paper believes that public credit belongs to the category of general credit and is a special public goods；the public credit original data has the function of reproduction，the public credit information has the characteristics of openness and integrity；the boundary between public credit information and market credit information is fuzzy. With the development of the market economy，the latter will continue to transition to the former，and the public credit information generated by the internet public domain should be incorporated into the national public credit information platform for unified supervision and application. Compared with the credit system of developed countries，China’s social credit system will carry more functions，including government’s functions transformation，new market supervision，social management and many other institutional functions. This is an institutional choice that is in line with China’s national conditions.