Abstract: The concept of eco-efficiency integrates environmental performance with economic performance, which is in accord with ecological civilization construction and sustainable development strategy. Based on the panel data of 30 provincial economic units in China from 2004 to 2014,this article focused on the empirical estimation and the analysis of spatio-temporal correlation and spatial agglomeration of eco-efficiency through constructing a regional eco-efficiency evaluation model and exploratory spatial statistical analysis method. The driving factors in eco-efficiency evolution were also analyzed. The results show that, (1) Regional differentials of eco-efficiency are significant in China and shows a gradient descending pattern of "East, Middle, West and Northeast"; (2) Regional eco-efficiency shows the characteristics of significant positive spatial correlation and spatial agglomeration. The eco-efficiency of adjacent provinces affects each other, which implies that the spatial diffusion effects are remarkable. Hence, regional differentials and spatial factors cannot be ignored both in theory and in reality. (3) Factors, such as economic development level, environmental regulation, structural changes, open door policies and urbanization level, all significantly affect eco-efficiency. In order to improve the regional eco-efficiency in China, we should focus on the backward areas in the central and western regions.