Abstract: Breaking free from resource dependence and realizing industrial structure upgrading constitute the core issue for the sustainable development of resource-based cities. Based on the panel data of 113 resource-based cities in China from 2013 to 2022, it establishes a basic econometric regression model through the multi-period difference-in-differences（DID） method to evaluate the impact of the transformation pilot policy on the industrial structure upgrading of resource-based cities. Meanwhile, three mediating variables——green technological innovation, financial agglomeration and land resource allocation——are introduced to explore the influencing mechanism of the transformation pilot policy on industrial structure upgrading in resource-based cities. The research findings are as follows: ①the transformation pilot policy exerts a significant driving effect on the industrial structure upgrading of resource-based cities, and the conclusion remains robust after multiple robustness tests. ②Regional heterogeneity analysis reveals that the policy presents distinct heterogeneous effects on industrial structure upgrading of resource-based cities across different regions. It delivers a prominent promotional effect in central, northeastern and western China, while such effect is insignificant in eastern China. ③Mechanism analysis indicates that green technological innovation, financial agglomeration and land resource allocation serve as indirect transmission paths through which the policy facilitates the industrial structure upgrading of resource-based cities. Based on the research conclusions, this paper proposes to establish a long-term support mechanism for the transformation pilot program, strengthen the three major transmission channels of green technological innovation, financial agglomeration and land resource allocation, and implement targeted and regionally differentiated policies, so as to steadily and continuously unleash the policy’s driving effect on the industrial structure upgrading of resource-based cities.