Dongting Lake is a biodiversity hotspot and an important food production base. Small mammals in the area are mainly rodents, which not only pose a threat to food security but also to human health. Alexandromys fortis and Apodemus agrarius are the main rodents in the area. Previously, their habitats were relatively separated, but in recent years, with changes in environmental conditions, they have invaded each other. In order to achieve effective management of rodents in Dongting Lake, long-term monitoring of land use types and rodent communities was conducted for 20 years. The results showed that the construction land continued to increase, and the arable land and forest land remained stable. During this period, there was no significant relationship between the density of A. fortis and A. agrarius and the area of different land use types, but the fatness of A. fortis was significantly correlated with water body area and construction land area. The research suggests that fatness is more suitable and sensitive than population density during the rodent monitoring.