Under the background of "Green Belt and Road", exploring the transition path from "high energy consumption and high pollution" to green development in regions along the “Belt and Road" is of great significance for achieving the healthy and sustainable development of the economy. The current study decomposes the industrial eco-economic system into manufacturing subsystems and environmental protection subsystems, separately establishes the eco-efficiency evaluation index system of the two subsystems, and introduces the grey system theory’s "small sample and poor information" uncertainty problem into the TOPSIS-DEA cross- efficiency model to construct Grey TOPSIS-DEA model to measure the eco- efficiency of China’s key provinces along the "Belt and Road" from 2005 to 2016. On this basis, this paper analyzes the differences in the contribution rate of production factor to eco-efficiency growth in various regions. The results show that: the eco-efficiency of the whole industrial eco-economic system and the manufacturing subsystem of China's key provinces along the "Belt and Road" presents a general downward trend, with a slight fluctuation in the middle, and the eco-efficiency of the "One Belt" regions is lower than that of the "One Road" regions. The eco-efficiency of environmental protection subsystems in most regions along the line shows an increasing trend, and it is significantly lower than that of the industrial eco-economic system and the manufacturing subsystem. In addition, for High Manufacturing-High Environmental Protection areas, the contribution of labor to the improvement of eco-efficiency is the largest, and for other three types of areas, capital plays the most crucial role in improving eco-efficiency.