Abstract The paper compared the changes of fos-expression between Norway rats（Rattus norregicus）bred in laboratory and Wistar rats after they were exposed to cat urine odor for 0d, 1d, 3d, 6d, 9d and 18d by using immunohistochemistry, and investigated the influence of the living environment on the anti-predator strategy of Norway rats. The average optical densities of fos in Norway rats exposed to cat odor for different numbers of days in four brain regions（AHP, VMHC, MeAD and BLA）were significantly higher than those of the control group and there were no gender difference. Compared with the control group, the average optical density of fos in hypothalamus（AHP, VMHC）and amygdala （BLA） of Wistar rats exposed to cat odor significantly increased at 1d, 3d, 6d and 9d but not at 18d. The average optical densities of fos in AHP and MeAD were significantly different between males and females, but they were not different in VMHC and BLA for Wistar rats. During exposure to cat odor, the relative change rate of the average optical densities of fos（AHP, VMHC, MeAD, BLA）in Norway rats and Wistar rats also were different. This indicates that the living environment and exposure time can affect the response of Norway rats to predator odor.