Since the reform and opening up more than forty years ago, China has become the second-largest economy in the world. The rapid economic growth has brought the bitter fruits of an industrialized economy, resulting in serious environmental pollution and over-exploitation of resources, etc. The severe environmental conditions and economic downward pressure have forced the Chinese government and people to pay attention to the sustainable development issue. This paper focuses on the role of government audit in green accounting and sustainable development and proposes two research hypotheses, respectively, that government audit is conducive to enhancing sustainable development and that government audit promotes sustainable development by improving the development of green accounting in enterprises. This paper’s explanatory variables are set by constructing the domain-wide productivity index of the SBM directional distance function. The benchmark regression model and the mediation effect model are both used to test the two hypotheses. The two research hypotheses are verified individually using the empirical analysis method. Combined with the impact of government auditing to promote sustainable development, the role played by the government as a facilitator is analyzed. The correlation coefficient between government auditing and the level of sustainable development is 0.0275, which is significant at the 5% level. And government auditing expenditures can promote the level of sustainable development, which is consistent with hypothesis 1. At the same time, when the intensity of government auditing is less than the threshold value of 2.1525, the impact coefficient of green accounting on sustainable development is −0.0753. When the intensity of government auditing is greater than the threshold value of 2.1525, the impact coefficient is 0.2458, which indicates that when the intensity of government auditing is greater, the regulatory function can play a good role, so the impact of green accounting on the sustainable development of the region plays the incremental dynamic regulatory role, hypothesis 2 is valid.