Abstract: It is a necessary condition for resource-based cities to promote the transformation and upgrading of industrial structure and realize sustainable development by developing productive service industry to promote industrial co-agglomeration. Based on the panel data of 115 resource-based cities from 2005 to 2017, this paper empirically tested the effect, influence mechanism and spatial spillover effect of industrial co-agglomeration on sustainable development. The results showed that: (1) industrial synergy had a positive impact on the sustainable development of resource-based cities. Resource utilization efficiency, environmental pollution, technological progress and employment structure optimization were the influence mechanisms of industrial co-agglomeration affecting the sustainable development. (2) The promotion of sustainable development level was not only positively affected by its own industry co-agglomeration, but also by the positive spillover effect of industrial co-agglomeration in neighboring resource-based cities. The resource utilization efficiency and technological progress were the main channels of spillover effect. (3) In recent years, the direct effect of industrial co-agglomeration was relatively flat, with a long-term positive impact; spillover effect and total effect showed a rapid upward trend, and the impact had become positive one after another. At the same time, the spillover effect of industrial co-agglomeration had a certain effective distance threshold. This paper putted forward some policy suggestions to enhance the sustainable development ability of resource-based cities.