Abstract: Industrial eco-efficiency can reflect the relationship among economic development, environmental protection and resource conservation, so it is of great significance to explore the industrial ecological efficiency in Yangtze River Delta Urban Agglomerations. This paper firstly calculated the industrial eco-efficiency, and then explored the spatial and temporal evolution, regional differences, spillover effects and influencing factors. Some conclusions were drawn as follows. Over 2012-2016, both the average industrial eco-efficiency and absolute difference showed increasing trend, while the change in relative difference was little. The industrial eco-efficiency showed positive spatial correlation and high-eco-efficiency ‘club’ agglomeration. The industrial eco-efficiency of eastern regions was higher. It also presented an obvious spatial spillover effect. Besides, the evolution of the industrial eco-efficiency had the characteristic of obvious path dependence. The influence of industrial structure, scientific and technological input and economic development on industrial eco-efficiency was obvious. Investment in science and technology and economic development playen a significant role in promoting the local industrial eco-efficiency, while the industrial structure was not conducive to the improvement of local industrial eco-efficiency. The improvement of local urbanization was not conducive to the improvement of industrial eco-efficiency for neighboring cities. The local investment in science and technology and economic development were conducive to the improvement of industrial ecological efficiency for neighboring cities. Strengthening cooperation among cities had an important impact on improving industrial eco-efficiency.