Scientifically identifying the impact of urban development levels on the ecological environment in China’s grassland regions from a classification perspective is crucial for stabilizing grassland ecosystems and optimizing urban development in grassland cities. Using the Inner Mongolia Autonomous Region as a case study, this research constructs a conceptual analysis framework for the coordinated state between the urban development level and the ecological environment in China’s grassland regions based on the theory of dual economic structures. Employing the Granger causality test, nonlinear fitting, and coupling coordination degree model methods, the heterogeneity and coordination between urban development levels and ecological environment in China’s grassland areas from 2000 to 2020 are comprehensively analyzed. The findings reveal the following: (1) Capital-type central cities and growing resource-based cities, with high levels of development, positively nurture the grassland ecology, exhibit high labor mobility, and experience low endogenous and exogenous pressures, resulting in high coordination. (2) Pure agro-pastoral cities, with low development levels, negatively impact the grassland ecology, have low labor mobility, and face high endogenous and exogenous pressures, resulting in low coordination. (3) Regional central cities, with moderate development levels, exert a neutral counterbalance effect on the grassland ecology, with opposing endogenous and exogenous pressures, leading to moderate coordination. (4) When the impact relationship ranges from “positive-neutral-negative,” the endogenous and exogenous pressures on the grassland ecology by declining resource-based cities and developing agro-pastoral cities are determined by their specific development levels, showing variations from “large → balance → small” to “small → balance → large,” with coordination fluctuating between “high-moderate-low”. (5) Special ecological cities are less affected by urban development levels, with coordination levels determined by the ecological foundation. Analyzing the heterogeneous coordination between urban development levels and the ecological environment for different types of cities in grassland regions is significant for improving the overall quality of the grassland ecological environment and exploring distinctive urban development models.
