In recent years, human activities have significantly changed theterrestrial ecological environments. As an essential component of human activities, urbanization has a profound impact on the aquatic environment, which is one of terrestrial ecological environments. In this article, Hangzhou City was used as the research area, and the Hangzhou section of the BeijingHangzhou Grand Canal was taken as the research object. Based on the establishment of buffer zones with different radii for water quality monitoring sites, the impact of urban landscape patterns on the aquatic environment of river networks was analyzed. The results indicate that:(1) the urban and rural landscapes in the Hangzhou section of the Beijing-Hangzhou Grand Canal possess a mosaic structure, developed river network, high degree of landscape fragmentation, complex and diverse patch shape, typical characteristics of urban-rural fringe, and obvious differentiation of human activity intensity. (2) The spatial features of the various landscape types distributed along the river are very distinct. The landscape pattern index changes with the increase of the buffer radius. Once the buffer radius reaches 1000 meters, the landscape pattern index maintains a relatively stable state.(3) The content of nitrogen pollutants in the water system in the Hangzhou section of the Beijing-Hangzhou Grand Canal is generally at a high level, and the total phosphorus (TP) content is at a low level. Lands for construction and agriculture have a relatively high influence on water quality.(4) Different landscape pattern indexes have certain explanatory power for different water quality indexes during different periods, and the impact of the same landscape index on the aquatic environment in flood seasons and non-flood seasons is quite different and even opposite. The overall pros and cons of the impact of landscape pattern in dense river network urban areas on river aquatic environments need to be further weighted.