Abstract: This paper is the results of the survey and study on the black gibbons (Hylobates concolor) in Southwest Yunnan from October,1987,to March,1989.The gibbon population investigated in the mid-mountain humid evergreen broadleaf forest between 2,000 to 2,700 meters above sea level,was made up of 117 to 144 groups in Mt.Wuliang,and maybe next in Mt.Ailao,and few in Mt.Banma and Mt.Daxueshan.All the groups observed in these area were small,averaged 3.0±1.4(N=12,range=2-5) in size,and seemed to be monogamous.According to the observations on one group in Mt.Wuliang,the total amount of their active time was about 576±30 minutes (N=5,range=540-615),among them 3% for calling (15.8),14% for traveling (73.3),33% for feeding (180.8) and 50% for resting (273.3).The average day range length was about 795±153 meters (N=13,range=600-1,100),and home range was about 44-49 ha,in which 7.4 ha was utilized everyday.The results above have been compared with that of other species.