Since the reform and opening to outside world,the national debt plays more and more important role in China's economy in the fields of compensating financial deficit,raising construction funds and adjusting economic growth.The increase of the role of the national debt also increases the risk in the issue,use and return of the national debt.Thus,the overall study of the national debt is helpful to better giving the function of national debt into full play and to promoting the efficiency of the use of the national debt.