Abstract: The seasonal population fluctuations in gray hamster show that the peak density occurs in June-October, but the heighest density in house mouse is in October.Multi-yearly population dynamics of gray hamster are smaller than that of house mouse. 3 litters are born in gray hamster throughout a year, while in house mouse 9 .39 litters are born in a year.Therefore, gray hamster population cann't lead to larger damage than house mouse.