Based on 31 provincial governments in China from 2005 to 2016， this paper constructs a dynamic panel data model to study the relationship between government audit and local government debt growth and its mechanism from the perspective of fiscal decentralization. The study finds that government audit can restrain the growth of local government debt， and the effect of income increase and expenditure saving can play a more inhibitory role in the low-debt-scale provinces， and the effect of establishing a sound system can play a more inhibitory role in the high-debt-scale provinces. Further research finds that the effect of government audit on local government debt governance is different in fiscal decentralization system. The higher the fiscal decentralization is， the stronger the restraint effect of government audit on the growth of local government debt will be. The study has a theoretical and practical significance for the government audit giving full play the effect of local government debt governance and preventing the risk of local government debt.