Long term deficit finance has become a common feature of the major economies in the world. In the development of human society，the former risk-taking subjects such as traditional community and nuclear family have been deconstructed. At the same time，the weakening of human individual behavior choice constraints has formed a tense relationship with the proliferation of negative externalities of human behavior，which constitutes the main contradiction of the risk society. The government has to take on more and more public risks. Fiscal deficit is a temporary response plan against the background of a large transformation from private risk to public risk. To completely resolve the fiscal deficit and the corresponding risks，we need a profound transformation of government functions.