The global development process is currently confronted with unprecedented challenges, such as food, energy, climate change, geopolitics, and other crises. The inequality and imbalance in global development are very serious, and developing countries, especially vulnerable countries, are seriously impacted. Help "the belt and road initiative" (BRI will be used from now on) seek high-quality development on the basis of development and strive for parallel quantity and quality. Based on the input-output index system of energy efficiency in the BRI, this paper calculates the energy efficiency of 58 countries in the BRI from 2005 to 2019 using the Super-SBM model and analyzes the spatial evolution of energy use efficiency in the economies along the route. The results show that: (1) Montenegro, Armenia, Israel, Singapore, Brunei, Slovenia, and Latvia are the top seven countries in the field of average annual energy efficiency, while Mongolia, Kazakhstan, Iran, Uzbekistan, Syria, Ukraine, and Belarus are the bottom seven countries, which should be given attention in the follow-up development of the BRI. (2) Central and Eastern European countries have higher energy efficiency, while China and Mongolia have lower energy efficiency; (3) The average annual energy utilisation efficiency of developed nations is better than that of developing nations; (4) From another viewpoint of spatial evolution, BRI countries' energy efficiency demonstrates a downward tendency; (5) Regression analysis with the Tobit model shows that economic development as well as the percentage of renewable electricity have positive effects, while foreign trade, the electricity rate, and land area have negative effects on energy efficiency. By calculating the BRI's member countries' energy efficiency, it enriches the gaps in the existing research and provides valuable references for studying the green development of the BRI
