The activity rhythm of 28 house-hold sika deer was observed by using scan sampling and all-occurrence recording methods from April to August, 2007.The results showed the frequencies of eating, ruminating, relaxing, observing, removing and grooming behavior decreased by turns, and the frequencies of eating and relaxing behavior occupied 80% in all diurnal activities. There were two peaks for the frequencies of eating and ruminating at about 7:30 and 17:30.The peak for the frequencies of relaxing was from 11:00 to 14:00.The difference among the male, the female and the young in eating and relaxing behavior was analyzed, and the results showed there was significant difference in eating behavior in the period of 9:30-11:30 and 12:30-17:30 for the old and the young.In the period of 7:30-8:30, 9:30-10:30 and 12:30-17:30, there was significant difference in relaxing behavior between the male and the female.Our results can provide some basic theory for breeding and protecting sika deer.