Under the new normal background, reducing haze and increasing ecological efficiency is an important guarantee to promote the coordinated and sustainable development of cities. This paper first uses the panel data of 269 prefecture-level cities in China from 2008 to 2017, combined with ArcGIS spatial analysis and super-efficiency EBM-DEA model to explore the spatiotemporal evolution pattern of haze pollution and ecological efficiency. Secondly, this paper combines the spatial Durbin model (SDM) and partial differential equations to explore the nonlinear impact of industrial agglomeration on haze pollution and ecological efficiency and its spatial spillover effects. The results show that:(1) urban haze pollution in China has the characteristics of "blocky" and "cluster distribution", and presents a "core-edge" diffusion model centered on Beijing-Tianjin-Hebei urban agglomeration; The overall urban ecological efficiency is low, showing a decreasing trend in the order of East > Central > West, and its H-H cities are mainly distributed in the eastern coastal areas. (2) Industrial agglomeration is a double-edged sword, and its impact on haze pollution and ecological efficiency has a significant U-shaped relationship. Specifically, for every 1% increase in the industrial agglomeration, haze pollution and ecological efficiency will decrease by 0.1388% and 0.1409%, and every 1% increase in industrial agglomeration square items will increase by 0.0188% and 0.0113%. (3) Industrial agglomeration has a strong spatial spillover effect on haze pollution and ecological efficiency in local and neighboring cities. Specifically, industrial agglomeration has a significant negative spatial spillover effect on haze pollution and ecological efficiency in local and neighboring cities, while the further increase of industrial agglomeration has the opposite impact on haze pollution and ecological efficiency. Therefore, local governments should adopt a pollution control strategy of joint prevention and control to construct a long-term environmental governance cooperation mechanism. (4) The impact of industrial agglomeration scale on haze pollution and ecological efficiency shows strong regional heterogeneity. The ecological efficiency of high-value industrial agglomeration areas increased with the expansion of their agglomeration scale, while the low-value areas failed the significance test. This result indicates that government departments should actively formulate differentiated industrial development strategies to provide important support for cities to reduce haze and improve ecological efficiency. We proved the robustness of the above main conclusions by reconstructing the weight matrix, replacing the core explanatory variables and setting the lagged variables. China is currently in the critical stage of the transition from industrial civilization to ecological civilization, and it is hoped that this study can provide a reference for regional sustainable development.