Abstract: Understanding the wildlife behavior and habitat selection in closed nature reserve is fundamental in planning effective management. From September 2011 to August 2012, daily activity pattern of red deer was recorded using camera trapping technology for exploring its seasonal changes of activity rhythm at Saihanwula Nature Reserve, Inner Mongolia of northern China. The results showed that the daily activity rhythm of red deer exhibited significant seasonal differences(χ²=7.905, P=0.048). The activity intensities in autumn and winter were the strongest, and appeared an equal level in spring and summer. There was no difference between forest and forest-edge habitats in the aspect of intensity of daily activity intensity (Z=-0.210, P=0.834).Red deer showed two peak periods of activities at the dawn and dusk in the spring and summer (05:00 and 19:00 in spring, 00:00 and 20:00 in summer) possibly due to breeding requirements, food resources and climate conditions. The activities of red deer showed no significant difference in open and forest-edge habitats, indicating that the habitat structure features in this area had little influence on the activity rhythm. These results will contribute to monitoring on the seasonal habitat choices of the red deer and thus providing data for protecting wild animals more efficiently in the nature reserve.