© 2020 by the authors. This article investigates the effects of China's outward direct investment (ODI) on the institutional quality of the Belt and Road (B&R) countries. Based on a panel data set of 63 B&R countries during the period 2003 to 2016, we find that China's ODI improves the institutional quality of B&R countries not only in the short run but also in the long run. Further, although China's ODI exerts no differential impacts on host country institutional dimensions of "control of corruption, " "government effectiveness, " and "political stability" in countries with different natural resource endowments, it improves their institutional dimensions of "regulatory quality" and "rule of law, " implying that China's ODI may help the host B&R countries minimize the "resource curse". As one of the most important strategies for China's opening-up development in the current era, the B&R initiative serves as means to promote sustainable development of B&R countries. The article therefore contributes to existing scholarship on the institutional effects of China's ODI and sheds light on the mechanisms that drive sustainable development.