The economy and ecological aspects of a social system are coherently linked and can be examined by its material and energy flows. In this study, we used the material flow analysis (MFA) to model the material input and output of Wujin District of Changzhou City, Jiangsu Province. We found that: (1) the total material inputs and the material inputs per capita increased with economic development, while the total material outputs and material outputs per capita decreased consistently; (2) except water, the total material inputs continue to increase,and the input of solid materials grows faster than that of gaseous materials, while the total material outputs kept reducing; and the gas outputs counted the largest portion of the output, resulting the primary environmental pollution as fossil fuel burning; (3) agricultural water use continued increasing while industrial and residential water use decreased by per capita. The total wastewater emission and the emission per capita decreased, with a faster decreasing rate of residential wastewater emission followed by industrial wastewater emission; (4) the material inputs per unit GDP varied and the material outputs per unit GDP decreased. We also found a decreasing trend in both water use and wastewater emission per unit GDP. These results suggested that the efficiency of resource use in Wujin District has been accelerating as the economic and environmental changes are tightly coupled. Additionally, we discussed the harmonic development between environment and economy using the Wujin District as an example. Potential limitations of MFA’s application were also discussed for future research. Effective measures should be taken to raise the status and significance of practicing circular economy strategies in constructing the environmental balance of an economical system.