[Objective] The stages and regional differences in the industrial ecological level of the Hohhot-Baotou-Ordos-Yulin urban agglomeration were measured to understand the shortcomings of the industrial ecological level and formulate more scientific countermeasures and suggestions for the development of the urban agglomeration. [Methods] The evaluation index of industrial ecology was constructed by considering the following two aspects: industrial economic system and ecological environment system. The entropy method was employed to measure the level of industrial ecology in each city of the Hohhot-Baotou-Ordos-Yulin urban agglomeration from 2012 to 2021. The coupling coordination model was then used to analyze the degree of coupling and coordination between the industrial economic system and the ecological environment system in urban agglomeration. Finally, the fixed-effect model was utilized to analyze the influencing factors. [Results] ① From 2012 to 2021, the overall level of industrial ecology in the cities affected by Hohhot-Baotou-Ordos-Yulin urban agglomeration showed a fluctuating upward trend, and from the perspective of the average level for prefectures and cities, the development of industrial ecology level was unbalanced. ② From 2012 to 2021, the coupling degree of the industrial economic system and the ecological environment system of each city in the urban agglomerations was in the advanced coupling stage of dynamic change. The degree of coordination between cities had improved to varying degrees, but it was still poorly coordinated. In addition, the rate of development of coupling coordination was slow. ③ By analyzing the influencing factors of industrial ecology using the fixed-effect model, the results showed that the levels of economic development, opening to the outside world, technological innovation, comprehensive utilization of waste, and government regulation and control had a significant positive effect on the level of industrial ecology, whereas the industrial structure had a significant inhibitory effect on the level of industrial ecology. [Conclusion] The level of industrial ecology and coupling coordination degree of Hohhot-Baotou-Ordos-Yulin urban agglomeration requires significant enhancement. It is necessary to optimize the industrial structure and cultivate a diversified industrial system; promote circular development and improve the level of waste utilization; increase investment in innovation and enhance social innovation capabilities. Meanwhile, goveronment departments should actively participate, and give full play to the role of supervision.