： Improving the quality of urban development is the essence of high-quality economic development at the present stage. Urban sprawl in the process of urbanization in China has become an important factor that affects the quality of urban development. Using panel data of 285 cities in China from 2004 to 2017, this study empirically investigated the heterogeneous relationship between urban sprawl and green total factor productivity. The research found that: (1) Moderate urban sprawl improved green total factor productivity, while excessive urban sprawl inhibited or did not significantly affect green total factor productivity; (2) Considering regional differences of population agglomeration, urban sprawl had a prominent promoting effect on green total factor productivity in the eastern region, while having more inhibitory effects on the central and western regions; (3) As the economy exceeded the optimal agglomeration thresholds, the inverse correlation became a co-directional relationship. Furthermore, there was a significant inverted U-shaped threshold effect based on manufacturing agglomeration. However, in cities with a higher degree of service industry agglomeration, the promotional effect of urban sprawl is not significant. This study deepens the understanding of the basic pattern of urban sprawl affecting green development of cities. It provides a beneficial reference for the top-level design of high-quality urban development and is of significance for China’s promotion of leading urban agglomeration with central cities and new urbanization strategy.