The global debt outstanding reached a new peak in 2018. By analyzing the composition of debt in three dimensions：internal and external，public and private，and servicing cost，this paper points out that the rapid increase of private debt （non-financial enterprise loan） is an important new feature of global debt development. For developing countries，the increasing share of short-term debt，non-government/bank debt ownership，debt investment in unproductive areas，and the new situation brought about by the above-mentioned new changes-although debt indicators are relatively low compared with developed economies，the risk of debt crisis is rising rapidly-have become important features. The current debt situation in developing countries is not supportive to the realization of the UN 2030 Sustainable Development Goals. China’s productive investment in developing countries under the “Belt and Road Initiative” will alleviate the long-term debt pressure of developing countries by promoting local economic development.