Abstract: The result shows that rodenticide significantly affected the structure of the mammal community, and the effect differed with rat killing time and frequency.When rat killing in autumn,the small mammal density declined year by year,and reached a low level after three years, with a decrease of community diversity and a weak recovery. When rat killing in spring,the density could be kept at a low level,however,the diversity was higher than other treatments,with a strongcapacity of restoring the biodiversity. Increasing the frequency of rodenticide application intensified the effect on decreasing the density of small mammals. Therefore, chemical rat controlling obviously decreased the density of small mammals and the diversity of the community, and promoted the community succession with more prominent dominant species, monotonous community composition and unstable structure direction.

Key words: Rodenticide, Chlorophacinone, Small mammal in farmland, Community, Diversity, Succession