The concept of scale effect curve of public debt, as an academic idea, was proposed by Jia Kang in the 1990s. Public debt (including both national and local government debt) is an important tool for governments to raise funds, alleviate fiscal pressure, and implement macroeconomic regulation and modern financial management. However, there has been ongoing debate about the optimal scale of national debt and whether there exists an objective, reasonable limit. One perspective, derived from Keynesian “government debt is not really debt” theory, argues that since “government debt is not debt,” governments can continuously roll over old debt with new debt, suggesting that there is no need to worry about the scale of the debt. In response, Jia Kang, in his theoretical research on the moderate scale of national debt (including both national and local government debt), proposed the concept of a “scale effect curve of public debt.”