Public debt was issued in 1776 in the United States. In the American history of the public debt, its main characters were presenting several cycles definitely, showing the peculiarity of financial assets and the variety of it's creditor. The aim to issue public debt was to raise money for the wars and resolve the problem of economic crisis, simultaneity, it had played an important role in offsetting the government budget deficits. However, all the impacts of the public debt in financial support for the governmental expenditures, intervening the economic activities of the government, and adjusting for the microeconomic plan of the United States were obviously in the past more than 200 years. Comparing to the United States, China's public debt was issued for raising money for the economic construction and offsetting the budget deficits, not for the wars. The positive effects of the public debt was to solve the problem of insufficiency in domestic demand after 1998. Nowadays, China's government is carrying out the strategy policy of building a well-off society in an all-round way, fundamentally, based on the experience and practice of the United States and China itself, public debt will be the bridge and tache in the economic constructing and redistributing the social resources. The positive effects of public debt will be exerted absolutely in the procedure of fulfilling the tasks of building a well-off society in an all-round way.