Abstract: The behaviors of sub-adult giant pandas (Ailuropoda melanoleuca) under two different captive conditions (3 pandas in traditional enclosures and 9 in semi-natural enclosures) were studied in China Conservation and Research Center for the Giant Panda,Wolong Nature Reserve from Jul.to Aug.2001.The duration and the frequency of behaviors were recorded by continuous observation.The findings demonstrate that sub-adults in traditional enclosures spent more time in investigating behavior and marking behavior than those in semi-natural enclosures,and stereotypic behavior of sub-adults in traditional enclosures had an increasing trend yet the difference didnt reach statistic significance.The duration of stereotypic behavior was significantly and positively correlated with the frequency of marking behavior and the duration of investigating behavior.These results indicate that the improvement of captive conditions can help to reduce the time sub-adult giant pandas spend on investigating behavior and the frequency of marking behavior.