Most of China’s resource-based cities are recently threatened by the problems of environmental pollution, resource depletion, and even economic recession. There is an urgent need for these cities to decouple economic growth from environmental degradation through improving resource utilization efficiency and eco-efficiency. This paper quantitatively evaluates the decoupling trends between GDP and environmental damage in major Chinese resource-based cities using big data. To explore the decoupling trends in the development of 115 resource-based cities in China, we develops a model to evaluate the eco-efficiency between economic growth and environmental pollution. Industrial pollutants are used as indicators of environmental degradation and GDP as an index for economic growth. This study finds diverse decoupling levels among the cities and that nearly one-third are developing unsustainably. The cities have encountered serious environmental problems due to past economic policies which have encouraged extensive GDP growth for the past 4 decades. This study demonstrates that the urban development and environmental protection of Chinese resource-based cities are not on a good path. It will be more difficult for the cities with quicker GDP growth to achieve a satisfactory decoupling trend. Therefore, there is an urgent need for industries to undertake resource-conserving and environmental protection measures, and, particularly, endorse technology innovation and the green economy. In order to achieve an overall balanced decoupling in China’s resource-based cities, it is essential for local governments to encourage environmentally friendly behaviors and enhance eco-efficiency when developing the country’s economy. Finally, the findings illustrate significant unbalanced decoupling levels across Chinese resource-based cities.