Microplastic pollution is an emerging threat to global freshwater ecological security. The emission and discharge of microplastic pollutants is highly associated with human activities and, therefore, cities are particularly at risk of microplastic pollution because they are a concentrated zone of plastic industry and use. Urban rivers may also be significant in transporting microplastic pollution from cities to other areas. Because of rapid urbanization, Chinese coastal cities are potentially at increasing risks of microplastic pollution from freshwater, atmospheric and terrestrial environments. Previous studies discovered that urban factors, including local population density, economic structures, and land-use patterns play decisive roles in microplastic pollution in China’s urban catchments. This study builds on past work by analysing the relationship between urban factors and freshwater microplastic pollution along an urban river channel in Ningbo, a megalopolis on the East Coast of China. The microplastic abundance in the Fenghua River, Ningbo, was compared to equivalent measures in other research. This study also considers local urban developments, revealing some of the core factors affecting urban microplastic pollution levels. This manuscript ultimately aims to find countermeasures for controlling China’s urban microplastic pollution. These measures will also provide some new perspectives for Chinese cities to deal with the spread and emission of other artificial contaminants in the future, so as to maintain the sustainable development in China, and extensively to other cities in the region.