Apodemus agrarius is one of the important pest rodents in farmland and broadly distributes in China. Since the establishment of the Three Gorges Project in 2003, the structure of rodent community has been evolving in Lake Dongting beach. A large number of A. agrarius has invaded the lake beach, and gradually dominated the community. The status of animals reproductive in a new habitat is one of the key indicator for understanding their adaptation to environment. It may provide scientific basis for further understanding the adaptation mechanism of A. agrarius after its invasion. It is also useful for the prediction and ecological prevention of A. agrarius. This study provided a comparative analysis of the reproductive status of A. agrarius caught in the lake beach and farmland habitat during 2003-2020 in Lake Dongting area, and analyzed their adaptability to the lake beach habitat in terms of reproduction in combination with seasonal dynamics and habitat differences. The results showed that: (1) The average reproductive index of A. agrarius was 0.71±0.27, which was lower than 1.21±0.47 in the farmland habitat. The reproductive index of A. agrarius on the lake beach during 2016-2020 was 0.99, which was slightly higher than 0.96 in the farmland. (2) Pregnant mice in the lake beach habitat tended to have more offspring than those in the farmland habitat, and the proportion of pregnant mice with more than 6 fetuses (65.59%) was higher than that in the farmland habitat (49.10%). (3) Juveniles were found to be involved in reproduction in the lake beach habitat, and their reproductive index, participation rate, pregnancy rate, and the rate of testes in scrotum increased with age. (4) Spring and autumn were the main breeding seasons for A. agrarius in the lake beach habitat. Its reproductive index, the rate of breeding female and rate of pregnancy were significantly higher than those in summer and winter, while the female-male ratio was significantly lower than that in summer. (5) Different vegetation structures in the lake beach habitat had an effect on the reproduction of A. agrarius, and the reproductive ability of the A. agrarius was stronger in the lake beach habitat of Carex sp.+ Miscanthus sp., and weaker in the reed land and wood land. These results suggested that the A. agrarius had adapted to the lake beach habitat and there were some difference in reproductive characteristics of the beach habitats compared with those of traditional farmland habitats.